CBSE

Questions & Answers

CBSE - Grade - 10

Subject: Science

Chapter - 04 - Carbon and Its Compounds

Types of Questions

MCQ
Fill in the Blanks
Name the following
Answer in one word
Find the Odd man out
Assertion & Reason
Match the Pair
True or False
Short Answer Questions
Long Answer Questions
Give Reasons
Puzzles
Arrange the Words*
Case Study
Difference Between
Numericals (for certain subjects only)

MCQ

The percentage of carbon in Earth’s crust is about:
a) 0.02%
b) 0.2%
c) 2%
d) 20%
Answer: a) 0.02%
The atomic number of carbon is:
a) 8
b) 6
c) 12
d) 14
Answer: b) 6
The electronic configuration of carbon is:
a) 1,5
b) 2,4
c) 2,6
d) 4,2
Answer: b) 2,4
Carbon needs how many electrons to complete its octet?
a) 2
b) 3
c) 4
d) 6
Answer: c) 4
Carbon forms bonds by:
a) Losing electrons
b) Gaining electrons
c) Sharing electrons
d) Donating protons
Answer: c) Sharing electrons
The bonds formed by sharing of electrons are called:
a) Ionic bonds
b) Metallic bonds
c) Covalent bonds
d) Hydrogen bonds
Answer: c) Covalent bonds
Which of the following is an example of a covalent compound?
a) NaCl
b) MgCl₂
c) CH₄
d) CaO
Answer: c) CH₄
Covalent compounds generally have:
a) High melting points
b) Low melting points
c) Free ions
d) Metallic character
Answer: b) Low melting points
Which of these is an allotrope of carbon?
a) Graphite
b) Diamond
c) Fullerene
d) All of these
Answer: d) All of these
The hardest natural substance is:
a) Graphite
b) Diamond
c) Fullerene
d) Coal
Answer: b) Diamond
Which allotrope of carbon conducts electricity?
a) Diamond
b) Graphite
c) Fullerene
d) Charcoal
Answer: b) Graphite
The molecular formula of Buckminsterfullerene is:
a) C₆₀
b) C₆
c) C₆₀H₆₀
d) C₆₀O
Answer: a) C₆₀
The ability of carbon to form long chains with itself is called:
a) Tetravalency
b) Catenation
c) Isomerism
d) Polymerisation
Answer: b) Catenation
Carbon can form stable bonds with:
a) Hydrogen
b) Oxygen
c) Nitrogen
d) All of these
Answer: d) All of these
Compounds containing only single covalent bonds are called:
a) Saturated compounds
b) Unsaturated compounds
c) Aromatic compounds
d) Alloys
Answer: a) Saturated compounds
Ethane (C₂H₆) is an example of:
a) Alkene
b) Alkyne
c) Alkane
d) Aromatic hydrocarbon
Answer: c) Alkane
Ethene (C₂H₄) is an example of:
a) Alkane
b) Alkene
c) Alkyne
d) Alcohol
Answer: b) Alkene
Ethyne (C₂H₂) is an example of:
a) Alkane
b) Alkene
c) Alkyne
d) Ketone
Answer: c) Alkyne
Compounds with same molecular formula but different structures are called:
a) Isotopes
b) Isomers
c) Isobars
d) Homologues
Answer: b) Isomers
Cyclohexane is an example of:
a) Straight chain compound
b) Branched chain compound
c) Ring compound
d) Aromatic compound
Answer: c) Ring compound
The functional group –OH represents:
a) Alcohol
b) Aldehyde
c) Carboxylic acid
d) Ketone
Answer: a) Alcohol
The functional group –COOH represents:
a) Aldehyde
b) Carboxylic acid
c) Ketone
d) Alcohol
Answer: b) Carboxylic acid
The functional group –CHO represents:
a) Alcohol
b) Ketone
c) Aldehyde
d) Ether
Answer: c) Aldehyde
The functional group C=O within a chain represents:
a) Aldehyde
b) Ketone
c) Carboxylic acid
d) Ester
Answer: b) Ketone
The general difference between two successive members of a homologous series is:
a) –CH₄–
b) –CH₃–
c) –CH₂–
d) –C₂H₆–
Answer: c) –CH₂–
Which of the following is NOT a member of the alkane series?
a) CH₄
b) C₂H₆
c) C₃H₈
d) C₂H₄
Answer: d) C₂H₄
IUPAC name of CH₃–CH₂–OH is:
a) Methanol
b) Ethanol
c) Propanol
d) Ethanoic acid
Answer: b) Ethanol
IUPAC name of CH₃–COOH is:
a) Methanol
b) Ethanol
c) Ethanoic acid
d) Methanoic acid
Answer: c) Ethanoic acid
IUPAC name of CH₃–CH₂–CH₃ is:
a) Ethane
b) Propane
c) Butane
d) Pentane
Answer: b) Propane
Combustion of hydrocarbons produces:
a) CO₂ and H₂O
b) CO only
c) O₂ only
d) H₂ only
Answer: a) CO₂ and H₂O
Which oxidising agent is used for oxidation of alcohols to acids?
a) HCl
b) NaOH
c) KMnO₄
d) H₂O
Answer: c) KMnO₄
The addition reaction is characteristic of:
a) Alkanes
b) Alkenes and Alkynes
c) Alcohols
d) Ketones
Answer: b) Alkenes and Alkynes
Substitution reactions are shown by:
a) Alkanes
b) Alkenes
c) Alkynes
d) Ketones
Answer: a) Alkanes
CH₄ + Cl₂ (sunlight) → ?
a) CH₃Cl + HCl
b) CCl₄ + H₂
c) CH₃OH
d) C₂H₆
Answer: a) CH₃Cl + HCl
Formula of ethanol is:
a) CH₃OH
b) C₂H₅OH
c) CH₃COOH
d) C₂H₄
Answer: b) C₂H₅OH
Ethanol reacts with sodium to form:
a) Sodium acetate + H₂
b) Sodium ethoxide + H₂
c) Sodium chloride + H₂
d) Sodium carbonate + H₂
Answer: b) Sodium ethoxide + H₂
Dehydration of ethanol using conc. H₂SO₄ gives:
a) Ethane
b) Ethene
c) Ethyne
d) Methane
Answer: b) Ethene
Vinegar is a dilute solution of:
a) Methanoic acid
b) Ethanoic acid
c) Propanoic acid
d) Hydrochloric acid
Answer: b) Ethanoic acid
Ethanoic acid reacts with ethanol to form:
a) Aldehyde
b) Ester
c) Ketone
d) Salt
Answer: b) Ester
Esters have:
a) Pungent smell
b) Sweet smell
c) Rotten smell
d) No smell
Answer: b) Sweet smell
Ethanoic acid reacts with sodium carbonate to produce:
a) CO₂
b) H₂
c) CH₄
d) O₂
Answer: a) CO₂
The freezing point of glacial acetic acid is:
a) 373 K
b) 290 K
c) 273 K
d) 200 K
Answer: b) 290 K
Soaps are:
a) Sodium or potassium salts of carboxylic acids
b) Sodium or potassium salts of sulphonic acids
c) Hydrocarbons
d) Proteins
Answer: a) Sodium or potassium salts of carboxylic acids
The cleansing action of soap is due to formation of:
a) Scum
b) Micelles
c) Crystals
d) Bubbles only
Answer: b) Micelles
In soap micelles, the hydrophobic tails are:
a) Outwards in water
b) Inwards away from water
c) Both sides equally
d) Randomly placed
Answer: b) Inwards away from water
Soap is not effective in hard water because:
a) It forms scum with calcium and magnesium ions
b) It dissolves quickly
c) It evaporates
d) It forms crystals
Answer: a) It forms scum with calcium and magnesium ions
Detergents are effective in hard water because:
a) They are stronger acids
b) They do not form insoluble salts with Ca²⁺ and Mg²⁺
c) They evaporate faster
d) They act only in soft water
Answer: b) They do not form insoluble salts with Ca²⁺ and Mg²⁺
Which of the following is a use of ethanol?
a) Fuel
b) Solvent
c) Alcoholic beverages
d) All of these
Answer: d) All of these
Which of the following is a use of ethanoic acid?
a) Preservative
b) Ester formation
c) Vinegar
d) All of these
Answer: d) All of these
Which property of carbon explains the large number of organic compounds?
a) Combustion
b) Catenation and Tetravalency
c) Allotropy
d) Oxidation
Answer: b) Catenation and Tetravalency

Fill in the Blanks

The percentage of carbon in Earth’s crust is about ______.
Answer: 0.02%
The percentage of carbon in the atmosphere is about ______.
Answer: 0.03%
The atomic number of carbon is ______.
Answer: 6
The electronic configuration of carbon is ______.
Answer: 2,4
Carbon needs ______ electrons to complete its octet.
Answer: 4
Carbon forms bonds by ______ of electrons.
Answer: sharing
Bonds formed by sharing of electrons are called ______ bonds.
Answer: covalent
Methane (CH₄) contains ______ single covalent bonds.
Answer: 4
Oxygen (O₂) contains a ______ bond.
Answer: double
Nitrogen (N₂) contains a ______ bond.
Answer: triple
Covalent compounds generally have ______ melting and boiling points.
Answer: low
Covalent compounds are ______ conductors of electricity.
Answer: poor
The hardest natural substance is ______.
Answer: diamond
______ is the allotrope of carbon which conducts electricity.
Answer: Graphite
Buckminsterfullerene has molecular formula ______.
Answer: C₆₀
The ability of carbon atoms to form chains with itself is called ______.
Answer: catenation
Carbon exhibits ______ due to having 4 valence electrons.
Answer: tetravalency
Compounds with only single bonds are called ______ compounds.
Answer: saturated
Compounds with double or triple bonds are called ______ compounds.
Answer: unsaturated
Ethane (C₂H₆) is an example of ______.
Answer: alkane
Ethene (C₂H₄) is an example of ______.
Answer: alkene
Ethyne (C₂H₂) is an example of ______.
Answer: alkyne
Compounds with the same molecular formula but different structures are called ______.
Answer: isomers
______ is an example of a ring compound.
Answer: Cyclohexane / Benzene
The functional group –OH represents ______.
Answer: alcohol
The functional group –COOH represents ______.
Answer: carboxylic acid
The functional group –CHO represents ______.
Answer: aldehyde
The functional group C=O in the middle of a chain represents ______.
Answer: ketone
Members of a homologous series differ by ______ unit.
Answer: –CH₂–
All members of a homologous series have similar ______ properties.
Answer: chemical
The IUPAC name of CH₃–CH₂–OH is ______.
Answer: ethanol
The IUPAC name of CH₃–COOH is ______.
Answer: ethanoic acid
The IUPAC name of CH₃–CH₂–CH₃ is ______.
Answer: propane
Combustion of hydrocarbons produces ______ and ______.
Answer: carbon dioxide, water
Alcohols are oxidised to carboxylic acids using ______.
Answer: KMnO₄ / K₂Cr₂O₇
The reaction in which hydrogen is added to an unsaturated hydrocarbon is called ______ reaction.
Answer: addition
The reaction in which Cl₂ replaces H in alkanes is called ______ reaction.
Answer: substitution
CH₄ + Cl₂ (sunlight) → ______ + HCl.
Answer: CH₃Cl
The molecular formula of ethanol is ______.
Answer: C₂H₅OH
Ethanol reacts with sodium to form ______ and hydrogen.
Answer: sodium ethoxide
Dehydration of ethanol gives ______.
Answer: ethene
Vinegar is a dilute solution of ______.
Answer: ethanoic acid
Ethanoic acid reacts with ethanol to form ______.
Answer: ester
Esters have a ______ smell.
Answer: sweet
Ethanoic acid reacts with sodium carbonate to release ______ gas.
Answer: carbon dioxide
The freezing point of glacial acetic acid is ______ K.
Answer: 290
Soaps are sodium or potassium salts of long-chain ______ acids.
Answer: carboxylic
The cleansing action of soap is due to formation of ______.
Answer: micelles
In soap micelles, the hydrophobic tails are directed ______.
Answer: inwards
Detergents are effective in ______ water.
Answer: hard

Name the Following

Name the element that forms the basis of organic chemistry.
Answer: Carbon
Name the element present only in 0.02% of Earth’s crust.
Answer: Carbon
Name the element with atomic number 6.
Answer: Carbon
Name the type of bond formed when carbon shares electrons.
Answer: Covalent bond
Name the allotrope of carbon which is the hardest natural substance.
Answer: Diamond
Name the allotrope of carbon which is a good conductor of electricity.
Answer: Graphite
Name the spherical allotrope of carbon containing 60 atoms.
Answer: Buckminsterfullerene (C₆₀)
Name the property of carbon to form long chains with itself.
Answer: Catenation
Name the property of carbon that allows it to form four bonds.
Answer: Tetravalency
Name the compounds containing only single bonds between carbon atoms.
Answer: Saturated compounds (Alkanes)
Name the compounds containing double bonds between carbon atoms.
Answer: Alkenes
Name the compounds containing triple bonds between carbon atoms.
Answer: Alkynes
Name the phenomenon where compounds have the same molecular formula but different structures.
Answer: Isomerism
Name a carbon compound with a ring structure.
Answer: Cyclohexane / Benzene
Name the functional group represented by –OH.
Answer: Alcohol
Name the functional group represented by –COOH.
Answer: Carboxylic acid
Name the functional group represented by –CHO.
Answer: Aldehyde
Name the functional group represented by C=O (in the middle of a chain).
Answer: Ketone
Name the series of compounds differing by –CH₂– unit.
Answer: Homologous series
Name the IUPAC system of naming carbon compounds.
Answer: IUPAC nomenclature
Name the IUPAC name of CH₃–CH₂–OH.
Answer: Ethanol
Name the IUPAC name of CH₃–COOH.
Answer: Ethanoic acid
Name the IUPAC name of CH₃–CH₂–CH₃.
Answer: Propane
Name the products of complete combustion of hydrocarbons.
Answer: Carbon dioxide and water
Name the reaction when alcohol is converted to acid using KMnO₄.
Answer: Oxidation
Name the reaction where hydrogen is added to an unsaturated compound.
Answer: Addition reaction
Name the reaction in which chlorine replaces hydrogen in alkanes.
Answer: Substitution reaction
Name the product formed when methane reacts with chlorine in sunlight.
Answer: Chloroform (CH₃Cl initially)
Name the gas evolved when ethanol reacts with sodium.
Answer: Hydrogen
Name the compound formed when ethanol is dehydrated with conc. H₂SO₄.
Answer: Ethene
Name the dilute solution of ethanoic acid used in kitchens.
Answer: Vinegar
Name the sweet-smelling product formed from ethanol and ethanoic acid.
Answer: Ester
Name the reaction between alcohol and carboxylic acid.
Answer: Esterification
Name the gas evolved when ethanoic acid reacts with sodium carbonate.
Answer: Carbon dioxide
Name the acid that freezes at 290 K and is called glacial acid.
Answer: Glacial acetic acid
Name the salts of long-chain carboxylic acids used for cleaning.
Answer: Soaps
Name the structure formed by soaps in water that trap dirt and oil.
Answer: Micelles
Name the part of soap molecule that is hydrophobic.
Answer: Hydrocarbon tail
Name the part of soap molecule that is hydrophilic.
Answer: Ionic head
Name the cleansing agent that works even in hard water.
Answer: Detergent
Name the gas released when ethanoic acid reacts with sodium bicarbonate.
Answer: Carbon dioxide
Name the alcohol commonly used in alcoholic drinks.
Answer: Ethanol
Name the alcohol obtained by fermentation of sugar.
Answer: Ethanol
Name the alcohol which is highly poisonous and not fit for drinking.
Answer: Methanol
Name one important industrial use of ethanol.
Answer: As a solvent / as a fuel
Name one important industrial use of ethanoic acid.
Answer: As a preservative / in ester preparation
Name the process in which unsaturated hydrocarbons become saturated by hydrogen.
Answer: Hydrogenation
Name the oxidising agents used to convert alcohols into acids.
Answer: Alkaline KMnO₄ / Acidified K₂Cr₂O₇
Name the two products obtained when ethanol burns completely in oxygen.
Answer: Carbon dioxide and water
Name the property of soaps that explains their cleansing action.
Answer: Micelle formation / Emulsification

Answer in One Word

Which element is the basis of organic chemistry?
Answer: Carbon
What is the atomic number of carbon?
Answer: 6
What type of bonds does carbon form by sharing electrons?
Answer: Covalent
What is the hardest natural substance known?
Answer: Diamond
Which allotrope of carbon conducts electricity?
Answer: Graphite
Which spherical carbon allotrope contains 60 atoms?
Answer: Fullerene
What property of carbon allows it to form long chains?
Answer: Catenation
What is the valency of carbon?
Answer: Four
Compounds with only single bonds are called?
Answer: Alkanes
Compounds with double bonds are called?
Answer: Alkenes
Compounds with triple bonds are called?
Answer: Alkynes
What is the simplest alkane?
Answer: Methane
What is the simplest alkene?
Answer: Ethene
What is the simplest alkyne?
Answer: Ethyne
What phenomenon is having the same molecular formula but different structures?
Answer: Isomerism
Which functional group is represented by –OH?
Answer: Alcohol
Which functional group is represented by –COOH?
Answer: Carboxylic acid
Which functional group is represented by –CHO?
Answer: Aldehyde
Which functional group is represented by C=O in the middle of a chain?
Answer: Ketone
Which series of compounds differ by –CH₂– unit?
Answer: Homologous
What is the IUPAC name of CH₃–CH₂–OH?
Answer: Ethanol
What is the IUPAC name of CH₃–COOH?
Answer: Ethanoic acid
Which compound is commonly known as vinegar?
Answer: Ethanoic acid
Which acid is also called glacial acid?
Answer: Acetic
Which compound is called grain alcohol?
Answer: Ethanol
Which compound is poisonous and used as a solvent?
Answer: Methanol
Which compound is formed when ethanol reacts with ethanoic acid?
Answer: Ester
Which reaction converts alcohol to acid using KMnO₄?
Answer: Oxidation
Which reaction adds hydrogen to unsaturated compounds?
Answer: Addition
Which reaction replaces hydrogen atoms in alkanes with chlorine?
Answer: Substitution
Which gas is evolved when sodium reacts with ethanol?
Answer: Hydrogen
Which gas is released when sodium carbonate reacts with ethanoic acid?
Answer: Carbon dioxide
Which compound is formed when ethanol is dehydrated by conc. H₂SO₄?
Answer: Ethene
Which catalyst is used in hydrogenation of vegetable oils?
Answer: Nickel
Which product is formed by complete combustion of ethanol besides water?
Answer: Carbon dioxide
Which compound is used as a preservative in pickles?
Answer: Vinegar
Which compounds are sodium or potassium salts of fatty acids?
Answer: Soaps
Which cleansing agents work in both soft and hard water?
Answer: Detergents
Which structures are formed by soap molecules trapping dirt?
Answer: Micelles
Which part of soap is hydrophobic?
Answer: Hydrocarbon tail
Which part of soap is hydrophilic?
Answer: Ionic head
What type of bonding is present in methane?
Answer: Covalent
Which alcohol is obtained by fermentation of sugar?
Answer: Ethanol
Which enzyme converts glucose to ethanol in fermentation?
Answer: Zymase
Which type of flame is produced when methane burns with sufficient oxygen?
Answer: Blue
Which type of flame is produced when methane burns with limited oxygen?
Answer: Yellow
Which gas is released when ethanoic acid reacts with sodium bicarbonate?
Answer: Carbon dioxide
Which type of reaction is esterification?
Answer: Condensation
Which type of compound is benzene?
Answer: Aromatic
Which property of carbon explains its ability to form millions of compounds?
Answer: Catenation

CBSE - Grade 10 - Science

All Chapters

Science
- Chapter 1 – Chemical Reactions and Equations
- Chapter 2 – Acids, Bases and Salts
- Chapter 3 – Metals and Non-metals
- Chapter 4 – Carbon and its Compounds
- Chapter 5 – Life Processes
- Chapter 6 – Control and Coordination
- Chapter 7 – How do Organisms Reproduce?
- Chapter 8 – Heredity
- Chapter 9 – Light – Reflection and Refraction
- Chapter 10 – The Human Eye and the Colourful World
- Chapter 11 – Electricity
- Chapter 12 – Magnetic Effects of Electric Current
- Chapter 13 – Our Environment

CBSE - Grade 10 - Mathematics

All Chapters

Ch 01 – Real Numbers
Ch 02 – Polynomials
Ch 03 – Pair of Linear Equations in Two Variables
Ch 04 – Quadratic Equations
Ch 05 – Arithmetic Progressions
Ch 06 – Triangles
Ch 07 – Coordinate Geometry
Ch 08 – Introduction to Trigonometry
Ch 09 – Some Applications of Trigonometry
Ch 10 – Circles
Ch 11 – Areas related to Circles
Ch 12 – Surface Areas and Volumes
Ch 13 – Statistics
Ch 14 – Probability

CBSE - Grade 10 - English - First Flights

All Chapters

A Letter to God
Dust of Snow
Fire and Ice
Nelson Mandela: A Long Walk to Freedom
A Tiger in the Zoo
Two Stories about Flying
His First Flight
Black Aeroplane
How to Tell Wild Animals
The Ball Poem
From the Diary of Anne Frank
Amanda!
Glimpses of India
A Baker from Goa
Coorg
III. Tea from Assam
The Trees
Mijbil the Otter
Fog
Madam Rides the Bus
The Tale of Custard the Dragon
The Sermon at Benares
For Anne Gregory
The Proposal

CBSE - Grade 10 - English - Words and Expressions

All Chapters

Unit 1 – A Letter to God
Unit 2 – Nelson Mandela: Long Walk to freedom
Unit 3 – Two stories about flying
Unit 4 – From the diary of Anne Frank
Unit 5 – Glimpses of India
Unit 6 – Mijbil the otter
Unit 7 – Madam rides the bus
Unit 8 – The sermon at Benaras
Unit 9 – The proposal

CBSE - Grade 10 - English - Supplementary Reader - Footprints without Feet

All Chapters

A Triumph of Surgery
The Thief’s Story
The Midnight Visitor
A Question of Trust
Footprints without Feet
The Making of a Scientist
The Necklace
Bholi
The Book That Saved the Earth

CBSE - Grade 10 - History

All Chapters

The Rise of Nationalism in Europe
Nationalism in India
The Making of a Global World
The Age of Industrialisation
Print Culture and the Modern World

CBSE - Grade 10 - Civics

All Chapters

Chapter 1 Power-sharing
Chapter 2 Federalism
Chapter 3 Gender, Religion and Caste
Chapter 4 Political Parties
Chapter 5 Outcomes of Democracy

CBSE - Grade 10 - Geography

All Chapters

Resources and Development
Forest and Wildlife Resources
Water Resources
Agriculture
Minerals and Energy Resources
Manufacturing Industries
Lifelines of National Economy

CBSE - Grade 10 - Economics

All Chapters

Ch 01 – Development
Ch 02 – Sectors of the Indian Economy
Ch 03 – Money and Credit
Ch 04 – Globalisation and the Indian Economy
Ch 05 – Consumer Rights

CBSE Grade 10

Find the Odd Man Out

Methane, Ethane, Propane, Ethene
Answer: Ethene
Explanation: Ethene is unsaturated, others are saturated alkanes.
Ethene, Ethyne, Propene, Methane
Answer: Methane
Explanation: Methane is saturated, others are unsaturated hydrocarbons.
Diamond, Graphite, Fullerene, Sodium
Answer: Sodium
Explanation: Sodium is a metal, others are carbon allotropes.
Alcohol, Aldehyde, Ketone, Chlorine
Answer: Chlorine
Explanation: Chlorine is an element, others are functional groups.
Methanol, Ethanol, Propanol, Methanoic acid
Answer: Methanoic acid
Explanation: Methanoic acid is a carboxylic acid, others are alcohols.
Vinegar, Acetic acid, Glacial acetic acid, Propanol
Answer: Propanol
Explanation: Propanol is an alcohol, others are forms of ethanoic acid.
Ethane, Ethene, Ethyne, Benzene
Answer: Ethane
Explanation: Ethane is saturated, others are unsaturated/aromatic.
Methanol, Ethanol, Butanol, Butanoic acid
Answer: Butanoic acid
Explanation: Butanoic acid is a carboxylic acid, others are alcohols.
Soap, Detergent, Shampoo, Propane
Answer: Propane
Explanation: Propane is a hydrocarbon fuel, others are cleansing agents.
Carbon dioxide, Water, Carbon monoxide, Methane
Answer: Methane
Explanation: Methane is a hydrocarbon, others are oxides of C and H.
Ethane, Propane, Butane, Ethanoic acid
Answer: Ethanoic acid
Explanation: Ethanoic acid is a carboxylic acid, others are alkanes.
Ethanol, Butanol, Pentanol, Butanoic acid
Answer: Butanoic acid
Explanation: Butanoic acid is a carboxylic acid, others are alcohols.
Soap, Detergent, Vinegar, Shampoo
Answer: Vinegar
Explanation: Vinegar is acetic acid, others are cleansing agents.
Methane, Propane, Butane, Propene
Answer: Propene
Explanation: Propene is unsaturated, others are saturated alkanes.
Addition, Substitution, Esterification, Photosynthesis
Answer: Photosynthesis
Explanation: Photosynthesis is a biological process, others are organic reactions.
Ethene, Ethyne, Benzene, Propane
Answer: Propane
Explanation: Propane is saturated, others are unsaturated/aromatic.
Nickel, Platinum, Palladium, Sodium
Answer: Sodium
Explanation: Sodium is not used as a hydrogenation catalyst, others are.
Methane, Ethane, Propane, Methanol
Answer: Methanol
Explanation: Methanol is an alcohol, others are alkanes.
Diamond, Graphite, Fullerene, Chalk
Answer: Chalk
Explanation: Chalk is calcium carbonate, others are allotropes of carbon.
Methane, Ethane, Acetylene, Butane
Answer: Acetylene
Explanation: Acetylene is alkyne, others are alkanes.
Ethanol, Ethanoic acid, Ethyl alcohol, Propanol
Answer: Ethanoic acid
Explanation: Ethanoic acid is a carboxylic acid, others are alcohols.
Methanol, Ethanol, Vinegar, Propanol
Answer: Vinegar
Explanation: Vinegar is acetic acid, others are alcohols.
Hydrogen, Oxygen, Carbon dioxide, Methane
Answer: Methane
Explanation: Methane is hydrocarbon fuel, others are elements/oxides.
Ethanol, Methanol, Butanol, Formaldehyde
Answer: Formaldehyde
Explanation: Formaldehyde is an aldehyde, others are alcohols.
Esterification, Substitution, Addition, Neutralisation
Answer: Neutralisation
Explanation: Neutralisation is acid-base reaction, others are organic reactions.
Benzene, Toluene, Naphthalene, Ethane
Answer: Ethane
Explanation: Ethane is saturated, others are aromatic hydrocarbons.
Catenation, Tetravalency, Isomerism, Photosynthesis
Answer: Photosynthesis
Explanation: Photosynthesis is biological, others are carbon properties.
Ethanol, Methanol, Glucose, Propanol
Answer: Glucose
Explanation: Glucose is a carbohydrate, others are alcohols.
Ester, Aldehyde, Ketone, Oxygen
Answer: Oxygen
Explanation: Oxygen is an element, others are functional groups.
Butane, Pentane, Hexane, Ethanol
Answer: Ethanol
Explanation: Ethanol is alcohol, others are alkanes.
Ethane, Propane, Butane, Ethene
Answer: Ethene
Explanation: Ethene is unsaturated, others are alkanes.
Vinegar, Glacial acetic acid, Ethanol, Acetic acid
Answer: Ethanol
Explanation: Ethanol is alcohol, others are forms of ethanoic acid.
Soap, Detergent, Micelle, Methane
Answer: Methane
Explanation: Methane is a fuel, others are cleansing related.
Methanol, Ethanol, Propanol, Butanoic acid
Answer: Butanoic acid
Explanation: Butanoic acid is carboxylic acid, others are alcohols.
Propane, Butane, Pentane, Propanoic acid
Answer: Propanoic acid
Explanation: Propanoic acid is carboxylic acid, others are alkanes.
Diamond, Graphite, Charcoal, Sodium chloride
Answer: Sodium chloride
Explanation: Sodium chloride is ionic salt, others are carbon allotropes.
Ethane, Ethene, Ethyne, Chlorine
Answer: Chlorine
Explanation: Chlorine is an element, others are hydrocarbons.
Methane, Ethane, Ethene, Ethanoic acid
Answer: Ethanoic acid
Explanation: Ethanoic acid is carboxylic acid, others are hydrocarbons.
Formaldehyde, Acetaldehyde, Acetone, Ethanol
Answer: Ethanol
Explanation: Ethanol is an alcohol, others are aldehyde/ketone.
Methane, Propane, Butane, Ethanol
Answer: Ethanol
Explanation: Ethanol is alcohol, others are alkanes.
Ethanol, Methanol, Ethanoic acid, Propanol
Answer: Ethanoic acid
Explanation: Ethanoic acid is carboxylic acid, others are alcohols.
Saturated, Unsaturated, Aromatic, Alkali
Answer: Alkali
Explanation: Alkali is a base, others are classes of hydrocarbons.
Ethanol, Vinegar, Glacial acetic acid, Acetic acid
Answer: Ethanol
Explanation: Ethanol is alcohol, others are forms of ethanoic acid.
Methane, Ethane, Ethyne, Butane
Answer: Ethyne
Explanation: Ethyne is an alkyne, others are alkanes.
Catenation, Tetravalency, Combustion, Isomerism
Answer: Combustion
Explanation: Combustion is a reaction, others are properties of carbon.
Propane, Butane, Pentane, Benzene
Answer: Benzene
Explanation: Benzene is aromatic, others are alkanes.
Methanol, Ethanol, Butanol, Acetone
Answer: Acetone
Explanation: Acetone is a ketone, others are alcohols.
Ethanol, Methanol, Ethanoic acid, Propanol
Answer: Ethanoic acid
Explanation: Ethanoic acid is acid, others are alcohols.
Esterification, Neutralisation, Substitution, Addition
Answer: Neutralisation
Explanation: Neutralisation is acid-base reaction, others are organic reactions.
Soap, Detergent, Micelle, Vinegar
Answer: Vinegar
Explanation: Vinegar is acid, others are cleansing related.

Match the Pair

Set 1

Match the following:
Column A:

Diamond
Graphite
Fullerene
Methane
Ethanol

Column B:
a. Conducts electricity
b. Hardest substance
c. Simplest alkane
d. Alcohol
e. Football-shaped molecule

Answers:
1 – b
2 – a
3 – e
4 – c
5 – d

Set 2

Match the following:
Column A:

Catenation
Tetravalency
Alkanes
Alkenes
Alkynes

Column B:
a. Triple bond
b. Property of carbon forming long chains
c. Single bond hydrocarbons
d. Double bond hydrocarbons
e. Carbon forms 4 bonds

Answers:
1 – b
2 – e
3 – c
4 – d
5 – a

Set 3

Match the following:
Column A:

Isomerism
Homologous series
Functional group
Ethanoic acid
Methanol

Column B:
a. Poisonous alcohol
b. Same molecular formula, different structures
c. Group of atoms giving special properties
d. Differs by –CH₂– unit
e. Vinegar

Answers:
1 – b
2 – d
3 – c
4 – e
5 – a

Set 4

Match the following:
Column A:

Alcohol functional group
Carboxylic acid functional group
Aldehyde functional group
Ketone functional group
Hydroxyl group

Column B:
a. –OH
b. –COOH
c. –CHO
d. –OH (in alcohols)
e. C=O (in middle of chain)

Answers:
1 – d
2 – b
3 – c
4 – e
5 – a

Set 5

Match the following:
Column A:

Esterification
Hydrogenation
Oxidation
Substitution reaction
Addition reaction

Column B:
a. Converts unsaturated compounds to saturated
b. Alcohol + acid → ester
c. Replacement of atom by another
d. Alcohol → acid
e. Adds atoms across double or triple bond

Answers:
1 – b
2 – a
3 – d
4 – c
5 – e

Set 6

Match the following:
Column A:

Ethene
Ethyne
Ethanoic acid
Methane
Ethanol

Column B:
a. Simplest alkyne
b. Simplest alkane
c. Used in vinegar
d. Used in alcoholic drinks
e. Simplest alkene

Answers:
1 – e
2 – a
3 – c
4 – b
5 – d

Set 7

Match the following:
Column A:

Soap
Detergent
Micelle
Hard water
Scum

Column B:
a. Insoluble calcium and magnesium salts
b. Cleansing agent effective in soft water only
c. Cleansing agent effective in both soft and hard water
d. Structure formed by soap molecules trapping dirt
e. Contains Ca²⁺ and Mg²⁺ ions

Answers:
1 – b
2 – c
3 – d
4 – e
5 – a

Set 8

Match the following:
Column A:

Saturated hydrocarbons
Unsaturated hydrocarbons
Methane combustion
Limited oxygen combustion
Complete combustion

Column B:
a. Yellow flame, soot formation
b. Single bonds only
c. Double or triple bonds present
d. Blue flame with CO₂ and H₂O
e. CH₄ + O₂ → CO₂ + H₂O

Answers:
1 – b
2 – c
3 – e
4 – a
5 – d

Set 9

Match the following:
Column A:

Zymase
Fermentation
Glucose → ethanol
Conc. H₂SO₄
Nickel catalyst

Column B:
a. Catalyst for hydrogenation
b. Dehydrating agent converting ethanol to ethene
c. Enzyme used in fermentation
d. Process of glucose to ethanol
e. Chemical change producing ethanol

Answers:
1 – c
2 – d
3 – e
4 – b
5 – a

Set 10

Match the following:
Column A:

Diamond structure
Graphite layers
Fullerene
Benzene
Carbon monoxide

Column B:
a. Ring structure with delocalised electrons
b. Spherical molecule with 60 carbons
c. Each atom bonded to four others in 3D network
d. Toxic gas binding strongly with hemoglobin
e. Layers that slide, making soft

Answers:
1 – c
2 – e
3 – b
4 – a
5 – d

Short Answer Questions

What is the valency of carbon?
Answer: The valency of carbon is four.
Why does carbon form covalent bonds?
Answer: Carbon shares electrons because it cannot easily lose or gain four electrons.
What is catenation?
Answer: Catenation is the property of carbon to form long chains with itself.
Name the three allotropes of carbon.
Answer: The three allotropes of carbon are diamond, graphite, and fullerene.
Why is diamond hard?
Answer: Diamond is hard because each carbon atom is bonded to four others in a 3D network.
Why is graphite a good conductor of electricity?
Answer: Graphite conducts electricity due to free electrons between its layers.
What is the molecular formula of methane?
Answer: The molecular formula of methane is CH₄.
What type of bond exists in methane?
Answer: Methane contains single covalent bonds.
Name the simplest alkene.
Answer: The simplest alkene is ethene (C₂H₄).
Name the simplest alkyne.
Answer: The simplest alkyne is ethyne (C₂H₂).
What is isomerism?
Answer: Isomerism is the existence of compounds with the same molecular formula but different structures.
What is a homologous series?
Answer: A homologous series is a group of compounds with the same functional group differing by a –CH₂– unit.
Give one example of a homologous series.
Answer: Alkanes like CH₄, C₂H₆, and C₃H₈ form a homologous series.
What is the functional group of alcohols?
Answer: The functional group of alcohols is –OH.
What is the functional group of carboxylic acids?
Answer: The functional group of carboxylic acids is –COOH.
What is the functional group of aldehydes?
Answer: The functional group of aldehydes is –CHO.
What is the functional group of ketones?
Answer: The functional group of ketones is C=O (in the middle of a chain).
What is the IUPAC name of CH₃–CH₂–OH?
Answer: The IUPAC name is ethanol.
What is the IUPAC name of CH₃–COOH?
Answer: The IUPAC name is ethanoic acid.
What is vinegar?
Answer: Vinegar is a dilute solution of ethanoic acid.
Why is acetic acid called glacial acid?
Answer: Acetic acid is called glacial acid because it freezes at 290 K.
Why is methanol poisonous?
Answer: Methanol is poisonous because it affects the optic nerve and can cause blindness.
Name the enzyme that converts glucose to ethanol during fermentation.
Answer: The enzyme is zymase.
Write the reaction of ethanol with sodium.
Answer: Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas.
What gas is released when ethanoic acid reacts with sodium bicarbonate?
Answer: Carbon dioxide gas is released.
What type of flame is produced by complete combustion of methane?
Answer: Complete combustion produces a blue flame.
What type of flame is produced by incomplete combustion of hydrocarbons?
Answer: Incomplete combustion produces a yellow flame with soot.
What is esterification?
Answer: Esterification is the reaction of an alcohol with a carboxylic acid to form an ester.
What is the smell of esters?
Answer: Esters have a sweet, fruity smell.
What is saponification?
Answer: Saponification is the reaction of an ester with a base to form soap and alcohol.
What are soaps chemically?
Answer: Soaps are sodium or potassium salts of long-chain fatty acids.
Why do soaps not work well in hard water?
Answer: Soaps form insoluble scum with calcium and magnesium ions in hard water.
Why are detergents effective in hard water?
Answer: Detergents do not form scum with calcium and magnesium ions.
What is a micelle?
Answer: A micelle is a spherical structure formed by soap molecules trapping dirt.
Which part of soap is hydrophobic?
Answer: The hydrocarbon tail is hydrophobic.
Which part of soap is hydrophilic?
Answer: The ionic head is hydrophilic.
What is hydrogenation?
Answer: Hydrogenation is the addition of hydrogen to unsaturated hydrocarbons in the presence of a nickel catalyst.
Which catalyst is used in hydrogenation of vegetable oils?
Answer: Nickel is used as a catalyst.
What is substitution reaction?
Answer: Substitution reaction is the replacement of an atom in a compound by another atom.
What is addition reaction?
Answer: Addition reaction is the addition of atoms to unsaturated hydrocarbons.
Which compound is commonly known as grain alcohol?
Answer: Ethanol is called grain alcohol.
Which acid is used in esterification as a catalyst?
Answer: Concentrated sulphuric acid is used as a catalyst.
Which gas is released when ethanol burns completely?
Answer: Carbon dioxide is released.
What is the common use of ethanol?
Answer: Ethanol is used in alcoholic drinks, medicines, and as a fuel.
What is the common use of ethanoic acid?
Answer: Ethanoic acid is used as vinegar and food preservative.
Why are covalent compounds generally poor conductors?
Answer: They do not have free ions or electrons.
Why do covalent compounds have low melting and boiling points?
Answer: They have weak intermolecular forces of attraction.
What is benzene?
Answer: Benzene is an aromatic hydrocarbon with a ring structure.
What is carbon monoxide?
Answer: Carbon monoxide is a poisonous gas that binds strongly with hemoglobin.
Why does carbon form a large number of compounds?
Answer: Carbon forms a large number of compounds due to tetravalency and catenation.

Puzzles

I am a solid form of carbon, extremely hard, and used in cutting tools. I am…
Answer: Diamond
I am a soft form of carbon, used in pencils, and I conduct electricity. I am…
Answer: Graphite
I am a spherical molecule made entirely of carbon, also called a buckyball. I am…
Answer: Fullerene
I am a four-carbon alkane with straight chain structure. I am…
Answer: Butane
I am an unsaturated hydrocarbon with a double bond between carbon atoms. I am…
Answer: Alkene
I am an unsaturated hydrocarbon with a triple bond between carbon atoms. I am…
Answer: Alkyne
I am a functional group —OH, found in alcohols. I am…
Answer: Hydroxyl group
I am a functional group —COOH, responsible for acidic properties in compounds. I am…
Answer: Carboxyl group
I am a chemical reaction in which a compound reacts with oxygen to give CO₂ and H₂O. I am…
Answer: Combustion
I am a reaction where an unsaturated hydrocarbon reacts with hydrogen in the presence of a catalyst. I am…
Answer: Addition reaction
I am a reaction in which one atom or group in a compound is replaced by another. I am…
Answer: Substitution reaction
I am a liquid, soluble in water, used as a fuel and in alcoholic drinks. I am…
Answer: Ethanol
I am a weak acid found in vinegar, used in preservative and ester formation. I am…
Answer: Ethanoic acid
I am a salt of a long-chain carboxylic acid, used for cleaning and form micelles. I am…
Answer: Soap
I am a cleaning agent that works in hard water and does not form scum. I am…
Answer: Detergent
I am the ability of carbon to form long chains of carbon atoms. I am…
Answer: Catenation
I am the property of carbon to form four covalent bonds. I am…
Answer: Tetravalency
I am a series of organic compounds with the same functional group but differing by –CH₂– unit. I am…
Answer: Homologous series
I am an organic compound with only single bonds between carbon atoms. I am…
Answer: Alkane
I am an organic compound containing a carbonyl group (C=O) in the middle of the chain. I am…
Answer: Ketone
I am an organic compound containing a carbonyl group at the end of the chain. I am…
Answer: Aldehyde
I am a reaction where alcohol reacts with sodium metal to produce hydrogen gas. I am…
Answer: Reaction with sodium
I am a compound formed when an alcohol reacts with a carboxylic acid in the presence of acid. I am…
Answer: Ester
I am a compound responsible for fruity smell in perfumes. I am…
Answer: Ester
I am a greenhouse gas released during combustion of carbon compounds. I am…
Answer: Carbon dioxide
I am a poisonous gas formed due to incomplete combustion of carbon compounds. I am…
Answer: Carbon monoxide
I am the type of bond formed when carbon shares electrons with another atom. I am…
Answer: Covalent bond
I am the simplest alcohol with formula CH₃OH. I am…
Answer: Methanol
I am a method used to convert unsaturated vegetable oils into solid fats. I am…
Answer: Hydrogenation
I am the reaction where alcohol is dehydrated using concentrated H₂SO₄ to form an alkene. I am…
Answer: Dehydration reaction
I am the molecular formula of ethene. I am…
Answer: C₂H₄
I am the molecular formula of ethyne. I am…
Answer: C₂H₂
I am an organic compound used as fuel, solvent, and in medicines, formula C₂H₅OH. I am…
Answer: Ethanol
I am the organic acid in vinegar, formula CH₃COOH. I am…
Answer: Ethanoic acid
I am a long-chain hydrocarbon with only single bonds, also called saturated hydrocarbon. I am…
Answer: Alkane
I am a hydrocarbon with a double bond, more reactive than alkanes. I am…
Answer: Alkene
I am a hydrocarbon with a triple bond, highly reactive. I am…
Answer: Alkyne
I am a type of soap molecule with hydrophobic tail and hydrophilic head. I am…
Answer: Micelle
I am a type of detergent molecule that works in hard water. I am…
Answer: Synthetic detergent
I am the process by which soap removes oily dirt from clothes. I am…
Answer: Emulsification
I am a compound produced when soap reacts with hard water ions forming insoluble salts. I am…
Answer: Scum
I am the property of compounds that allows them to have the same molecular formula but different structures. I am…
Answer: Isomerism
I am the simplest alkane with one carbon atom. I am…
Answer: Methane
I am a gaseous fuel produced in marshes due to anaerobic decomposition. I am…
Answer: Marsh gas
I am the process of breaking double or triple bonds by adding hydrogen atoms. I am…
Answer: Hydrogenation
I am the compound CH₃—CH₂—CH₃. I am…
Answer: Propane
I am the compound CH₃—CH₂—OH. I am…
Answer: Ethanol
I am a compound formed by reaction between a carboxylic acid and alcohol. I am…
Answer: Ester
I am an acid that partially ionizes in water and turns blue litmus red. I am…
Answer: Ethanoic acid
I am a versatile element forming millions of compounds due to tetravalency and catenation. I am…
Answer: Carbon

Difference Between:

Difference between Diamond and Graphite

Answer:

Diamond: Each carbon atom bonded to 4 others in a 3D tetrahedral structure; very hard; does not conduct electricity; high melting point.
Graphite: Each carbon atom bonded to 3 others in layers; soft and slippery; conducts electricity; high melting point but lower than diamond.

Difference between Saturated and Unsaturated Hydrocarbons

Answer:

Saturated: Only single C–C bonds (alkanes); less reactive; general formula CₙH₂ₙ₊₂.
Unsaturated: Contains double or triple C–C bonds (alkenes/alkynes); more reactive; general formula CₙH₂ₙ (alkenes) or CₙH₂ₙ₋₂ (alkynes).

Difference between Alkanes and Alkenes

Answer:

Alkanes: Saturated hydrocarbons; single bonds only; less reactive; undergo substitution reactions.
Alkenes: Unsaturated hydrocarbons; contains double bonds; more reactive; undergo addition reactions.

Difference between Alcohol and Carboxylic Acid

Answer:

Alcohol: Contains –OH group; neutral or weakly acidic; reacts with sodium to produce H₂.
Carboxylic Acid: Contains –COOH group; acidic; reacts with metals and carbonates producing H₂ or CO₂.

Difference between Soap and Detergent

Answer:

Soap: Sodium or potassium salts of fatty acids; ineffective in hard water (forms scum).
Detergent: Synthetic cleaning agent; effective in hard water; does not form scum.

Difference between Homologous Series and Isomers

Answer:

Homologous Series: Compounds with same functional group, differ by –CH₂– unit; similar chemical properties, gradual change in physical properties.
Isomers: Compounds with same molecular formula but different structural arrangements; different physical and sometimes chemical properties.

Difference between Addition and Substitution Reaction

Answer:

Addition Reaction: Unsaturated compounds; double/triple bond is broken; new atoms added (e.g., H₂, Br₂).
Substitution Reaction: Saturated compounds; an atom/group replaced by another (e.g., CH₄ + Cl₂ → CH₃Cl + HCl).

Difference between Complete and Incomplete Combustion

Answer:

Complete Combustion: Hydrocarbon + O₂ → CO₂ + H₂O + heat; no smoke.
Incomplete Combustion: Hydrocarbon + limited O₂ → CO + C + H₂O; produces smoke/soot.

Difference between Methanol and Ethanol

Answer:

Methanol (CH₃OH): Simplest alcohol; highly toxic; used as solvent and fuel.
Ethanol (C₂H₅OH): Alcohol in beverages; less toxic than methanol; used as fuel, solvent, and drinks.

Difference between Catenation and Tetravalency

Answer:

Catenation: Carbon’s ability to form long chains, branched chains, and rings.
Tetravalency: Carbon forms four covalent bonds with other atoms to achieve stable electronic configuration.

Difference between Esterification and Oxidation of Alcohol

Answer:

Esterification: Alcohol + Carboxylic acid → Ester + Water; requires acid catalyst.
Oxidation: Alcohol → Aldehyde → Carboxylic acid; uses oxidizing agents (KMnO₄/K₂Cr₂O₇).

Difference between Hydrocarbon and Alcohol

Answer:

Hydrocarbon: Only C and H; non-polar; combustible.
Alcohol: Contains –OH group; polar; miscible with water; reacts differently than hydrocarbons.

Difference between Alkyne and Alkene

Answer:

Alkyne: Contains triple bond; general formula CₙH₂ₙ₋₂; more reactive than alkenes.
Alkene: Contains double bond; general formula CₙH₂ₙ; less reactive than alkynes.

Difference between Functional Group and Homologous Series

Answer:

Functional Group: Atom or group of atoms responsible for chemical property.
Homologous Series: Group of compounds with same functional group and gradually varying physical properties.

Difference between Diamond and Fullerene

Answer:

Diamond: 3D tetrahedral; hardest; does not conduct electricity; used in cutting tools.
Fullerene: Molecule like C₆₀; spherical; soft; conducts electricity; used in medicine, electronics.

Difference between Soap Molecule and Detergent Molecule

Answer:

Soap: Forms micelles; hydrophobic tail + hydrophilic head; ineffective in hard water.
Detergent: Similar structure; works in hard water; more effective cleaner.

Difference between Methane and Ethane

Answer:

Methane (CH₄): 1 carbon atom; gaseous at room temperature; simplest alkane.
Ethane (C₂H₆): 2 carbon atoms; gaseous at room temperature; next member of alkane series.

Difference between Alcohol and Ether

Answer:

Alcohol: Contains –OH group; polar; hydrogen bonding; miscible in water.
Ether: Contains –O– between carbons; less polar; lower boiling point; less reactive.

Difference between Aliphatic and Aromatic Compounds

Answer:

Aliphatic: Open chains or cyclic without benzene ring; includes alkanes, alkenes, alkynes.
Aromatic: Contains benzene ring; special stability; distinct reactions (electrophilic substitution).

Difference between Oxidation and Combustion

Answer:

Oxidation: Gain of oxygen or loss of hydrogen/electron; can be slow (e.g., alcohol → acid).
Combustion: Rapid reaction with oxygen producing heat and light; usually complete/incomplete combustion of hydrocarbons.

Assertion and Reason

Instructions:

For each question, choose the correct option:

(A) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(B) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(C) Assertion is true but Reason is false.
(D) Assertion is false but Reason is true.

Assertion: Carbon forms four covalent bonds.
Reason: The valency of carbon is 4.
Answer: (A)
Explanation: Both are true, and reason explains assertion.
Assertion: Diamond is hard.
Reason: Each carbon atom in diamond is bonded to three other atoms.
Answer: (C)
Explanation: Diamond has each carbon bonded to four atoms, not three.
Assertion: Graphite conducts electricity.
Reason: Graphite has free electrons due to delocalisation.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Fullerene is an allotrope of carbon.
Reason: It has a spherical structure of carbon atoms.
Answer: (A)
Explanation: Correct, C₆₀ fullerene is a spherical allotrope.
Assertion: Carbon compounds generally have high melting points.
Reason: Covalent bonds are weak.
Answer: (C)
Explanation: Carbon compounds usually have low melting points, and covalent bonds are strong.
Assertion: Methane is the first member of alkanes.
Reason: It contains one carbon atom bonded with four hydrogens.
Answer: (A)
Explanation: Both are true, and reason explains assertion.
Assertion: Ethene undergoes addition reactions.
Reason: Ethene has a double bond.
Answer: (A)
Explanation: Correct, addition occurs due to double bond.
Assertion: Ethyne is an alkyne.
Reason: It contains a triple bond between two carbons.
Answer: (A)
Explanation: True, reason explains assertion.
Assertion: Homologous series members show similar chemical properties.
Reason: They differ by –CH₂– unit.
Answer: (A)
Explanation: True, reason explains assertion.
Assertion: Isomers have different molecular formulas.
Reason: They have different arrangements of atoms.
Answer: (D)
Explanation: Isomers have same molecular formula but different arrangements.
Assertion: Ethanol is miscible with water.
Reason: Ethanol forms hydrogen bonds with water molecules.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Methanol is poisonous.
Reason: It produces formaldehyde and formic acid in the body.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Vinegar is used as a preservative.
Reason: Vinegar is a dilute solution of ethanoic acid.
Answer: (B)
Explanation: Both are true, but not explanatory.
Assertion: Ethanoic acid turns blue litmus red.
Reason: It is acidic in nature.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Ethanoic acid reacts with sodium carbonate to release CO₂.
Reason: Acids react with carbonates to produce CO₂.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Soaps are effective in hard water.
Reason: Hard water contains Ca²⁺ and Mg²⁺ ions.
Answer: (C)
Explanation: Soaps are not effective in hard water.
Assertion: Detergents are better than soaps in hard water.
Reason: Detergents do not form insoluble salts with Ca²⁺ and Mg²⁺.
Answer: (A)
Explanation: Correct, detergents remain effective.
Assertion: Soap molecules form micelles.
Reason: Soap molecules have hydrophilic heads and hydrophobic tails.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Esterification is a condensation reaction.
Reason: It involves the removal of water.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Hydrogenation converts oils into ghee.
Reason: Unsaturated compounds become saturated on adding hydrogen.
Answer: (A)
Explanation: Correct explanation.
Assertion: Carbon compounds are good conductors of electricity.
Reason: They contain covalent bonds.
Answer: (C)
Explanation: Most carbon compounds are poor conductors.
Assertion: Ethanol burns with a blue flame.
Reason: Ethanol is a carbon compound that undergoes complete combustion.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Acetic acid is called glacial acid.
Reason: It solidifies in cold climates.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Isomers have same molecular formula.
Reason: They differ in structural arrangement.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Carbon shows tetravalency.
Reason: It can neither gain nor lose 4 electrons easily.
Answer: (A)
Explanation: Correct, it shares electrons instead.
Assertion: Ethanoic acid reacts with alcohols to form esters.
Reason: Esters are sweet-smelling compounds.
Answer: (B)
Explanation: Both are true, but reason doesn’t explain reaction.
Assertion: Carbon forms strong bonds with other carbon atoms.
Reason: C–C bond is stable and strong.
Answer: (A)
Explanation: Both true, reason explains assertion.
Assertion: Alkanes are saturated hydrocarbons.
Reason: They have only single covalent bonds.
Answer: (A)
Explanation: True and reason explains assertion.
Assertion: Ethanoic acid reacts with sodium to release hydrogen.
Reason: Acids react with metals to release hydrogen gas.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Ethanoic acid reacts with base to form salt and water.
Reason: Acids neutralize bases.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Soap solution forms scum in hard water.
Reason: Insoluble calcium and magnesium salts are formed.
Answer: (A)
Explanation: Correct explanation.
Assertion: Micelles help in cleaning.
Reason: Dirt and grease get trapped in the hydrophobic tails.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Carbon monoxide is highly toxic.
Reason: It combines with hemoglobin more strongly than oxygen.
Answer: (A)
Explanation: Both true, correct explanation.
Assertion: Addition reaction takes place in saturated compounds.
Reason: Saturated compounds contain single bonds only.
Answer: (D)
Explanation: Addition happens in unsaturated compounds.
Assertion: Oxidation converts alcohol to acid.
Reason: Alcohol loses hydrogen and gains oxygen.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Methane burns with a yellow flame in limited oxygen.
Reason: Incomplete combustion forms carbon particles.
Answer: (A)
Explanation: Correct, soot causes yellow flame.
Assertion: Hydrocarbons are used as fuels.
Reason: They release large amounts of energy on combustion.
Answer: (A)
Explanation: Both true, reason explains assertion.
Assertion: Graphite is soft and slippery.
Reason: Layers of carbon atoms slide over each other.
Answer: (A)
Explanation: Correct explanation.
Assertion: Diamond conducts electricity.
Reason: It has delocalised electrons.
Answer: (D)
Explanation: Diamond does not conduct electricity.
Assertion: Fullerene resembles a football.
Reason: It contains 60 carbon atoms arranged in a sphere.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Carbon tetrachloride is used as a solvent.
Reason: It is a covalent compound and non-polar.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Benzene is an aromatic compound.
Reason: It contains a ring with delocalised electrons.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Detergents pollute water.
Reason: Detergents are non-biodegradable.
Answer: (A)
Explanation: Both true, correct explanation.
Assertion: Methane is a greenhouse gas.
Reason: It traps heat in the atmosphere.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Alcohols are volatile.
Reason: They have low boiling points compared to ionic compounds.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Alkenes are more reactive than alkanes.
Reason: Double bonds are more reactive than single bonds.
Answer: (A)
Explanation: Both true, reason explains assertion.
Assertion: Ethanol is used in medicines.
Reason: It acts as an antiseptic and solvent.
Answer: (A)
Explanation: Both true, reason explains assertion.
Assertion: Carbon forms giant covalent structures.
Reason: Both diamond and graphite are examples.
Answer: (A)
Explanation: Both are true, reason explains assertion.
Assertion: Acids turn phenolphthalein colourless.
Reason: Acids are proton donors.
Answer: (B)
Explanation: Both are true, but reason is not direct explanation.
Assertion: Carbon forms millions of compounds.
Reason: It shows catenation and tetravalency.
Answer: (A)
Explanation: Both are true, reason explains assertion.

True or False

Carbon has an atomic number of 6.
Answer: True
Carbon can easily form ionic bonds by losing or gaining 4 electrons.
Answer: False
Carbon completes its octet by sharing electrons.
Answer: True
Covalent bonds involve the sharing of electrons.
Answer: True
Covalent compounds usually have high melting and boiling points.
Answer: False
Diamond is the hardest natural substance.
Answer: True
Graphite is a good conductor of electricity.
Answer: True
Fullerene has a football-like structure.
Answer: True
Catenation is the ability of carbon to form chains with other carbon atoms.
Answer: True
Carbon is tetravalent.
Answer: True
Alkanes contain only single bonds.
Answer: True
Ethene is the simplest alkyne.
Answer: False
Ethyne contains a triple bond.
Answer: True
Structural isomers have the same molecular formula but different structures.
Answer: True
–OH represents a carboxylic acid group.
Answer: False
–COOH represents the carboxylic acid functional group.
Answer: True
–CHO represents an aldehyde group.
Answer: True
Ketones contain a –COOH group.
Answer: False
Homologous series differs by –CH₂– unit.
Answer: True
Alkanes, alkenes, and alkynes belong to homologous series.
Answer: True
The IUPAC name of CH₃–CH₂–OH is ethanol.
Answer: True
The IUPAC name of CH₃–COOH is methanoic acid.
Answer: False
Vinegar is a dilute solution of acetic acid.
Answer: True
Glacial acetic acid freezes at 290 K.
Answer: True
Methanol is safe for drinking in small quantities.
Answer: False
Excess intake of ethanol is harmful to health.
Answer: True
Oxidation of alcohols produces carboxylic acids.
Answer: True
Substitution reactions are common in alkanes.
Answer: True
Addition reactions are common in saturated hydrocarbons.
Answer: False
Hydrogenation converts unsaturated hydrocarbons into saturated ones.
Answer: True
Nickel is used as a catalyst in hydrogenation.
Answer: True
Combustion of methane in sufficient oxygen produces carbon dioxide and water.
Answer: True
In limited oxygen, hydrocarbons burn with a clean blue flame.
Answer: False
Ethanol reacts with sodium to produce hydrogen gas.
Answer: True
Ethanoic acid reacts with NaHCO₃ to produce carbon dioxide gas.
Answer: True
Esterification is a reaction between an alcohol and an acid.
Answer: True
Esters have a sweet smell.
Answer: True
Saponification is the reaction of esters with a base.
Answer: True
Soaps are sodium or potassium salts of carboxylic acids.
Answer: True
Detergents form scum in hard water.
Answer: False
Micelles are formed by soap molecules in water.
Answer: True
The hydrophobic tail of soap is attracted to water.
Answer: False
The hydrophilic head of soap interacts with water.
Answer: True
Benzene is an example of an aromatic compound.
Answer: True
Carbon monoxide is a harmless gas.
Answer: False
Carbon compounds are good conductors of electricity.
Answer: False
Covalent compounds generally dissolve in water.
Answer: False
Organic chemistry is the study of carbon compounds.
Answer: True
The enzyme zymase helps in fermentation of sugar to alcohol.
Answer: True
Carbon shows both catenation and tetravalency.
Answer: True

Long Answer Questions

Explain why carbon forms covalent bonds instead of ionic bonds.
Answer: Carbon has 4 valence electrons. To achieve a stable octet, it can either lose 4 electrons or gain 4 electrons. Losing 4 electrons would require high energy, and gaining 4 would make the nucleus unstable due to repulsion. Hence, carbon completes its octet by sharing electrons with other atoms, forming covalent bonds.
Define catenation. Explain how it helps in forming a large number of carbon compounds.
Answer: Catenation is the ability of carbon to form long chains, branched chains, and rings by bonding with other carbon atoms. This property, combined with tetravalency, allows carbon to form millions of stable compounds like alkanes, alkenes, alkynes, and aromatic hydrocarbons.
Differentiate between diamond and graphite in terms of structure and properties.
Answer: Diamond has a tetrahedral structure where each carbon is bonded to 4 other carbon atoms, making it extremely hard and a bad conductor of electricity. Graphite has a layered hexagonal structure where each carbon is bonded to 3 others, with free electrons that allow it to conduct electricity. Thus, diamond is used in cutting tools, while graphite is used as a lubricant and in electrodes.
Explain the structure of fullerenes. Give their uses.
Answer: Fullerenes are allotropes of carbon where atoms are arranged in hollow spheres, cages, or tubes. The most common is C₆₀, which resembles a football. Fullerenes are used in drug delivery, lubricants, and in nanotechnology due to their unique structure.
Why are covalent compounds generally poor conductors of electricity?
Answer: Covalent compounds consist of neutral molecules formed by sharing of electrons. They do not produce ions in aqueous solutions, hence cannot carry electric current, unlike ionic compounds.
What are homologous series? State its characteristics.
Answer: A homologous series is a group of organic compounds having the same functional group and general formula, with successive members differing by a –CH₂– unit. Characteristics: (i) Same functional group, (ii) Similar chemical properties, (iii) Gradual change in physical properties, (iv) Same general method of preparation, (v) Molecular masses increase by 14 units in successive members.
Write the structural differences between alkanes, alkenes, and alkynes.
Answer:

Alkanes: Saturated hydrocarbons with only single bonds, general formula CnH2n+2. Example: Methane (CH₄).
Alkenes: Unsaturated hydrocarbons with double bonds, general formula CnH2n. Example: Ethene (C₂H₄).
Alkynes: Unsaturated hydrocarbons with triple bonds, general formula CnH2n–2. Example: Ethyne (C₂H₂).

What is isomerism? Explain with examples.
Answer: Isomerism is the phenomenon where compounds have the same molecular formula but different structural arrangements. Example: Butane (C₄H₁₀) exists as n-butane (straight chain) and isobutane (branched chain). Both have different properties but same molecular formula.
Explain why alkanes undergo substitution reactions while alkenes undergo addition reactions.
Answer: Alkanes are saturated hydrocarbons; their single bonds are stable and do not break easily, so they react by substitution where one atom is replaced by another. Alkenes are unsaturated with double bonds, which break easily to allow addition of atoms, forming saturated compounds.
What is hydrogenation? Explain with an example and its industrial use.
Answer: Hydrogenation is the addition of hydrogen to unsaturated hydrocarbons in the presence of a catalyst (Ni, Pt, Pd), converting them into saturated compounds. Example: Ethene + H₂ → Ethane (with Ni catalyst). Industrial use: Converts vegetable oils into vanaspati ghee.
Write the IUPAC rules for naming carbon compounds.
Answer: (i) Select longest chain of carbon, (ii) Number chain from nearest functional group, (iii) Prefix for side chains, (iv) Suffix for functional groups (-ol, -al, -one, -oic acid), (v) Double/triple bond indicated by position number. Example: CH₃–CH₂–OH is named Ethanol.
Describe the reaction of ethanol with sodium metal.
Answer: Ethanol reacts with sodium to form sodium ethoxide and hydrogen gas.
Reaction: 2CH₃CH₂OH + 2Na → 2CH₃CH₂ONa + H₂↑
This shows ethanol has acidic hydrogen atoms.
Explain the reaction of ethanoic acid with sodium bicarbonate.
Answer: Ethanoic acid reacts with sodium bicarbonate to produce sodium ethanoate, water, and carbon dioxide gas.
Reaction: CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂↑
This reaction is used to test carboxylic acids.
What is esterification? Write its reaction.
Answer: Esterification is the reaction of an alcohol with a carboxylic acid in the presence of conc. H₂SO₄ to form esters and water.
Reaction: CH₃COOH + CH₃CH₂OH → CH₃COOCH₂CH₃ + H₂O
Esters have fruity smells and are used in perfumes.
What is saponification? Write its reaction.
Answer: Saponification is the hydrolysis of an ester with a base (NaOH or KOH) to form alcohol and sodium/potassium salt of acid (soap).
Reaction: CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH
Explain why soaps do not work well in hard water.
Answer: Hard water contains calcium and magnesium ions that react with soap to form insoluble calcium/magnesium salts (scum). This reduces the cleansing ability of soaps.
Why are detergents better than soaps in hard water?
Answer: Detergents are sodium salts of long-chain benzene sulphonic acids. They do not form insoluble salts with Ca²⁺ and Mg²⁺ ions in hard water, hence remain effective.
Explain micelle formation by soap molecules.
Answer: Soap molecules have a hydrophobic tail (nonpolar hydrocarbon) and hydrophilic head (-COO⁻ group). In water, they arrange into spherical clusters (micelles) where tails trap dirt/grease inside and heads face water, allowing dirt to be washed away.
What is fermentation of glucose? Write its reaction.
Answer: Fermentation is the breakdown of glucose by yeast enzyme zymase to form ethanol and carbon dioxide.
Reaction: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
Why is methanol considered poisonous?
Answer: Methanol is toxic because it is oxidized in the liver to formaldehyde and formic acid, which affect optic nerves, leading to blindness and even death.
Write the properties and uses of ethanol.
Answer: Properties: (i) Colorless liquid, (ii) Soluble in water, (iii) Burns with blue flame, (iv) Reacts with sodium, (v) Undergoes oxidation to acetic acid.
Uses: Solvent, fuel, alcoholic beverages, disinfectant, raw material for esters and chemicals.
Write the properties and uses of ethanoic acid.
Answer: Properties: (i) Colorless liquid with pungent smell, (ii) Soluble in water, (iii) Freezes at 290 K, (iv) Weak acid, (v) Reacts with carbonates and bases.
Uses: Preservative (vinegar), manufacture of esters, acetic anhydride, and cellulose acetate.
Explain complete combustion of hydrocarbons with an example.
Answer: In presence of sufficient oxygen, hydrocarbons burn completely to form carbon dioxide and water with release of heat.
Example: CH₄ + 2O₂ → CO₂ + 2H₂O + heat
This is used in fuels.
Explain incomplete combustion of hydrocarbons with an example.
Answer: In limited oxygen, hydrocarbons burn incompletely to form carbon monoxide and soot.
Example: 2CH₄ + 3O₂ → 2CO + 4H₂O
Incomplete combustion is dangerous as CO is poisonous.
Why does graphite conduct electricity but diamond does not?
Answer: Graphite has delocalized free electrons between layers, which move freely and conduct electricity. Diamond has no free electrons, so it cannot conduct.
What are functional groups? Give examples.
Answer: Functional groups are specific atoms/groups attached to carbon atoms that determine chemical properties of compounds. Examples: –OH (alcohol), –COOH (acid), –CHO (aldehyde), –CO– (ketone).
Give reasons why organic compounds are studied separately in chemistry.
Answer: Organic compounds are studied separately because carbon forms a very large number of stable compounds (millions), has unique catenation property, and forms covalent bonds with varied properties.
How are soaps prepared on a large scale?
Answer: Soaps are prepared by heating fats/oils with NaOH (saponification). The mixture is cooled, glycerol is removed, and soap is separated, hardened, and cut into bars.
Explain why detergents cause water pollution.
Answer: Some detergents are non-biodegradable. They remain in water bodies for a long time, causing foam and affecting aquatic life by reducing oxygen supply.
Describe the difference between saturated and unsaturated hydrocarbons with examples.
Answer: Saturated hydrocarbons contain only single bonds (alkanes) e.g., methane (CH₄). Unsaturated hydrocarbons contain double/triple bonds (alkenes/alkynes) e.g., ethene (C₂H₄), ethyne (C₂H₂). Unsaturated compounds are more reactive.
Explain substitution reaction in methane with chlorine.
Answer: Methane reacts with chlorine in presence of sunlight to form chloromethane and HCl.
CH₄ + Cl₂ → CH₃Cl + HCl
Further substitution can produce dichloromethane, trichloromethane, and tetrachloromethane.
Explain addition reaction in ethene with hydrogen.
Answer: Ethene reacts with hydrogen in the presence of nickel catalyst to form ethane.
CH₂=CH₂ + H₂ → CH₃–CH₃
This process is called hydrogenation.
Explain the oxidation of ethanol.
Answer: Ethanol is oxidized to ethanoic acid using alkaline KMnO₄ or acidified K₂Cr₂O₇ as oxidizing agents.
CH₃CH₂OH → CH₃COOH
Why does acetic acid turn blue litmus red but not conduct electricity strongly?
Answer: Acetic acid is a weak acid; it partially ionizes in water. Hence, it changes blue litmus to red but conducts weakly compared to strong acids like HCl.
How can you distinguish between ethanol and ethanoic acid?
Answer: Ethanol reacts with Na to release H₂ gas but does not react with NaHCO₃. Ethanoic acid reacts with both Na and NaHCO₃, releasing H₂ and CO₂ respectively.
Why do alkanes show a homologous series while carbonates and carbides are not considered organic?
Answer: Alkanes are covalently bonded hydrocarbons with –CH₂– difference. Carbonates and carbides are ionic compounds of carbon and do not exhibit covalent organic behavior, hence not studied under organic chemistry.
Write the role of concentrated sulphuric acid in esterification.
Answer: Conc. H₂SO₄ acts as a dehydrating agent, removing water formed in the reaction of alcohol and acid, and drives the reaction forward to produce esters.
How are esters hydrolyzed back to alcohol and acid?
Answer: On heating with dilute acid or base, esters undergo hydrolysis to give alcohol and carboxylic acid (or salt in case of base). This reaction is called saponification when base is used.
What is the difference between soaps and synthetic detergents?
Answer: Soaps are sodium/potassium salts of fatty acids; detergents are sodium salts of long-chain sulphonic acids. Soaps are ineffective in hard water, detergents are effective in both hard and soft water.
Explain why detergents are preferred over soaps in industry.
Answer: Detergents clean effectively in hard and soft water, do not form scum, can be used in acidic solutions, and are more suitable for industrial washing.
What are aromatic hydrocarbons? Give examples.
Answer: Aromatic hydrocarbons are cyclic compounds with delocalized π electrons following Huckel’s rule (4n+2). Example: Benzene, Toluene, Naphthalene.
What are the harmful effects of carbon monoxide?
Answer: Carbon monoxide combines with hemoglobin to form carboxyhemoglobin, reducing oxygen transport in blood. This causes headache, dizziness, unconsciousness, and even death.
Explain the difference between methane and ethane in terms of bonding and properties.
Answer: Methane (CH₄) is the simplest alkane with single bonds, colorless and odorless. Ethane (C₂H₆) has two carbons, burns with blue flame. Both are saturated, but ethane has higher molecular mass and boiling point.
Explain why covalent compounds have low melting and boiling points.
Answer: Covalent compounds consist of molecules held by weak intermolecular forces. These weak forces require little energy to overcome, hence they have low melting and boiling points.
What is vinegar? How is it produced and used?
Answer: Vinegar is a dilute solution of acetic acid (5–8%). It is produced by fermentation of ethanol using bacteria. Uses: Preservative, flavoring agent, cleaning agent.
What are biodegradable and non-biodegradable detergents?
Answer: Biodegradable detergents are broken down by microorganisms (linear chain detergents). Non-biodegradable detergents (branched chain) resist decomposition, cause pollution in water bodies.
How do soaps remove dirt?
Answer: Soap molecules form micelles in water. The hydrophobic tail attaches to grease while the hydrophilic head faces water. Dirt is trapped inside micelles and removed by rinsing with water.
Why is concentrated nitric acid not used directly in esterification?
Answer: Conc. HNO₃ is a strong oxidizing agent; it oxidizes alcohol instead of forming esters. Conc. H₂SO₄ is preferred as it acts only as a dehydrating agent.
What are saturated and unsaturated fats? How are they related to hydrogenation?
Answer: Saturated fats contain no double bonds (solid at room temperature), unsaturated fats contain double bonds (liquid oils). Hydrogenation adds hydrogen to unsaturated fats, converting them into saturated form (vanaspati ghee).
Write the importance of studying carbon compounds in daily life.
Answer: Carbon compounds are essential in fuels (coal, petroleum), food (carbohydrates, fats), medicines, plastics, fibers, cosmetics, detergents, and industrial chemicals. Understanding them helps in improving quality of life and developing new technologies.

Give Reasons

Give reason why carbon does not form ionic compounds.
Answer: Because gaining or losing 4 electrons requires very high energy, so carbon completes its octet by sharing electrons (covalent bonds).
Give reason why carbon shows catenation.
Answer: Carbon–carbon bonds are strong, stable, and can link repeatedly to form long chains, branched chains, and rings.
Give reason why carbon is tetravalent.
Answer: Carbon has 4 valence electrons and requires 4 more to complete its octet, hence it forms 4 covalent bonds.
Give reason why covalent compounds are generally poor conductors of electricity.
Answer: They do not form ions in solution and contain neutral molecules, so they cannot conduct electricity.
Give reason why covalent compounds have low melting and boiling points.
Answer: They are held by weak intermolecular forces of attraction, which require little energy to overcome.
Give reason why diamond is hard.
Answer: In diamond, each carbon atom is bonded to 4 others in a 3D tetrahedral network, making it rigid and hard.
Give reason why graphite conducts electricity.
Answer: Graphite has delocalized free electrons between layers that move and conduct electricity.
Give reason why diamond does not conduct electricity.
Answer: All four valence electrons are used in covalent bonding, so no free electrons are available for conduction.
Give reason why graphite is used as a lubricant.
Answer: Graphite has layered structure with weak forces between layers, so layers slide over each other easily.
Give reason why fullerenes are called ‘buckyballs’.
Answer: Because C₆₀ molecule has a spherical football-like structure similar to Buckminster Fuller’s geodesic dome.
Give reason why carbon forms millions of compounds.
Answer: Due to tetravalency, catenation, and ability to form stable covalent bonds with many elements.
Give reason why alkanes are called saturated hydrocarbons.
Answer: Because they contain only single bonds between carbon atoms.
Give reason why alkenes and alkynes are called unsaturated hydrocarbons.
Answer: Because they contain double or triple bonds between carbon atoms.
Give reason why alkanes undergo substitution reactions.
Answer: Because their single bonds are stable and do not break easily, so reaction occurs by replacement of hydrogen with other atoms.
Give reason why alkenes undergo addition reactions.
Answer: Because their double bonds are reactive and can break to add other atoms.
Give reason why alkynes are more reactive than alkanes.
Answer: Presence of triple bonds makes them highly unsaturated and reactive.
Give reason why isomers have different properties.
Answer: Though they have the same molecular formula, their structural arrangement differs, changing properties.
Give reason why ethanol is called a neutral compound.
Answer: Because it does not affect litmus paper and is neither strongly acidic nor strongly basic.
Give reason why ethanol reacts with sodium.
Answer: Because ethanol contains acidic hydrogen in –OH group, which reacts with sodium to liberate hydrogen gas.
Give reason why methanol is poisonous.
Answer: Methanol is oxidized in the liver to formaldehyde and formic acid, which damage optic nerves and cause blindness.
Give reason why ethanol is used as a fuel.
Answer: Because it burns with a clean flame producing carbon dioxide and water with high energy release.
Give reason why ethanoic acid is a weak acid.
Answer: Because it partially ionizes in aqueous solution, producing fewer H⁺ ions.
Give reason why ethanoic acid turns blue litmus red.
Answer: Because it releases H⁺ ions in water, showing acidic nature.
Give reason why ethanoic acid reacts with sodium bicarbonate.
Answer: Because acids react with carbonates/bicarbonates to produce carbon dioxide, water, and salt.
Give reason why esters have sweet smell.
Answer: Due to their molecular structure, esters release volatile aromatic vapors that smell fruity.
Give reason why conc. H₂SO₄ is used in esterification.
Answer: It acts as a dehydrating agent and removes water formed, shifting equilibrium towards ester formation.
Give reason why soaps are salts of fatty acids.
Answer: Because they are produced by saponification of fats/oils with NaOH or KOH.
Give reason why soaps form scum in hard water.
Answer: Because Ca²⁺ and Mg²⁺ ions in hard water react with soap to form insoluble salts (scum).
Give reason why detergents are better than soaps in hard water.
Answer: Because detergents do not form insoluble salts with Ca²⁺ and Mg²⁺ ions, hence remain effective.
Give reason why detergents are causing pollution.
Answer: Some detergents are non-biodegradable and persist in water bodies, causing foaming and harm to aquatic life.
Give reason why soap molecules form micelles in water.
Answer: Because hydrophobic tails attach to grease while hydrophilic heads face water, forming spherical structures.
Give reason why grease and dirt cannot be removed by water alone.
Answer: Because grease is non-polar and does not dissolve in polar water molecules.
Give reason why soap cleans better in hot water.
Answer: Hot water reduces viscosity of oil/grease and helps soap micelles trap dirt more efficiently.
Give reason why hydrogenation is used in industry.
Answer: To convert liquid vegetable oils into solid/semi-solid fats like vanaspati ghee.
Give reason why nickel is used in hydrogenation.
Answer: Nickel acts as a catalyst, increasing the rate of hydrogen addition reaction.
Give reason why hydrocarbons are used as fuels.
Answer: Because they undergo complete combustion releasing large amounts of energy.
Give reason why incomplete combustion of hydrocarbons is dangerous.
Answer: Because it produces carbon monoxide, a poisonous gas.
Give reason why CO is poisonous.
Answer: It combines with hemoglobin to form carboxyhemoglobin, reducing oxygen transport in blood.
Give reason why methane is called marsh gas.
Answer: Because it is produced naturally in marshy places by anaerobic decomposition of organic matter.
Give reason why covalent compounds are mostly insoluble in water.
Answer: Because they are non-polar and water is polar, so they do not mix well.
Give reason why organic chemistry is called the chemistry of life.
Answer: Because all living organisms are made up of organic compounds like proteins, fats, carbohydrates, and nucleic acids.
Give reason why benzene is called an aromatic hydrocarbon.
Answer: Because it has a cyclic structure with delocalized electrons and a characteristic aroma.
Give reason why vinegar is used as a preservative.
Answer: Because vinegar contains acetic acid, which prevents growth of microorganisms.
Give reason why concentrated nitric acid cannot be used in esterification.
Answer: Because it is a strong oxidizing agent and oxidizes alcohol instead of forming esters.
Give reason why esters are used in perfumes and flavorings.
Answer: Because they have pleasant fruity smells.
Give reason why carboxylic acids are stronger acids than alcohols.
Answer: Because carboxylic acids can stabilize the negative charge on –COO⁻ ion through resonance, unlike alcohols.
Give reason why organic compounds produce a sooty flame on burning.
Answer: Because unsaturated carbon compounds have higher carbon content and incomplete combustion produces soot.
Give reason why alkanes are less reactive.
Answer: Because they have strong C–C and C–H sigma bonds which do not break easily.
Give reason why organic solvents are used to dissolve covalent compounds.
Answer: Because like dissolves like – covalent compounds dissolve in non-polar organic solvents.
Give reason why carbon is considered unique among elements.
Answer: Because of its tetravalency, catenation, ability to form stable covalent bonds, and vast number of compounds.

Arrange the Words

Case Studies

Case Study 1

Rita was observing the structure of a diamond and graphite under a microscope. She noticed that diamond was very hard and graphite was soft and slippery.

Question: Explain why diamond is hard and graphite is soft.
Answer: Diamond has a 3D tetrahedral structure where each carbon is bonded to 4 others → very rigid. Graphite has layers of carbon bonded to 3 others, with weak forces between layers → soft and slippery.

Case Study 2

A student added sodium metal to a sample of ethanol and observed effervescence.

Question: Explain the reaction and the gas evolved.
Answer: Ethanol reacts with Na → C₂H₅ONa + H₂. Hydrogen gas is evolved due to the acidic hydrogen in –OH group.

Case Study 3

Vinegar was poured into a solution of sodium carbonate, and bubbles were observed.

Question: Name the gas produced and explain why bubbling occurs.
Answer: Gas produced is CO₂. Ethanoic acid reacts with Na₂CO₃ → NaCH₃COO + CO₂ + H₂O.

Case Study 4

During a lab experiment, a hydrocarbon burned completely, producing a colorless gas that turned lime water milky.

Question: Identify the gas and the type of hydrocarbon.
Answer: Gas is CO₂. Hydrocarbon undergoes complete combustion → could be alkane.

Case Study 5

A student observed that soap formed scum in hard water but detergents did not.

Question: Explain why this happens.
Answer: Soap reacts with Ca²⁺/Mg²⁺ ions in hard water → insoluble salts (scum). Detergents are not affected by Ca²⁺/Mg²⁺ → remain effective.

Case Study 6

During hydrogenation, liquid vegetable oil turned into solid fat.

Question: Name the reaction and catalyst used.
Answer: Hydrogenation; nickel (Ni) is used as the catalyst to convert unsaturated oils into saturated fats.

Case Study 7

A student observed that alkanes were less reactive than alkenes in a lab experiment.

Question: Give reason why alkanes are less reactive.
Answer: Alkanes have strong C–C and C–H sigma bonds → stable; alkenes have double bonds → reactive.

Case Study 8

Methanol ingestion caused poisoning in a person.

Question: Explain why methanol is toxic.
Answer: Methanol oxidizes in the liver to formaldehyde and formic acid → damages optic nerve → blindness.

Case Study 9

An ester with a fruity smell was prepared in the laboratory.

Question: Name the reaction used and the reactants.
Answer: Esterification; alcohol + carboxylic acid (in presence of conc. H₂SO₄) → ester + H₂O.

Case Study 10

A student tested an unknown compound in water and saw that it did not conduct electricity.

Question: Explain the type of compound and reason for non-conductivity.
Answer: Covalent compound; molecules are neutral → no free ions → poor conductivity.

Case Study 11

A hydrocarbon with formula C₂H₂ was tested with bromine water. The solution decolorized.

Question: Name the type of reaction and hydrocarbon.
Answer: Addition reaction; hydrocarbon is ethyne (alkyne).

Case Study 12

A person spilled ethanol on his hand and noticed it evaporated quickly.

Question: Explain why ethanol evaporates faster than water.
Answer: Ethanol has weaker hydrogen bonding and lower boiling point → faster evaporation.

Case Study 13

During combustion, incomplete burning of petrol in a car produced a toxic gas.

Question: Name the gas and its effect on human health.
Answer: Carbon monoxide (CO); binds with hemoglobin → reduces oxygen transport → poisonous.

Case Study 14

A student reacted alcohol with conc. H₂SO₄ and obtained a gas that burns with a pale blue flame.

Question: Name the reaction and the gas.
Answer: Dehydration of alcohol; gas formed is ethene.

Case Study 15

A hydrocarbon was observed to have straight, branched, and cyclic isomers.

Question: Give reason why these isomers exist.
Answer: Due to carbon’s catenation → same molecular formula can have different structural arrangements.

Case Study 16

A detergent was used to wash clothes in hard water, and the clothes became clean.

Question: Explain why detergent works in hard water.
Answer: Detergents do not form insoluble salts with Ca²⁺/Mg²⁺ ions → remain effective.

Case Study 17

A student observed sooty flame when kerosene burned incompletely.

Question: Explain why sooty flame appears.
Answer: High carbon content in hydrocarbon + incomplete combustion → carbon particles (soot) are formed.

Case Study 18

A student added bromine water to an unknown hydrocarbon, and the red color disappeared immediately.

Question: Identify the hydrocarbon and type of reaction.
Answer: Unsaturated hydrocarbon (alkene or alkyne); decolorization is due to addition reaction.

Case Study 19

Ethanol was used as a solvent to clean ink stains.

Question: Explain why ethanol works as a good solvent.
Answer: Ethanol is polar and can dissolve many organic and some inorganic compounds → good solvent.

Case Study 20

A student observed that soaps and detergents have hydrophilic heads and hydrophobic tails.

Question: Explain how this property helps in cleaning.
Answer: Hydrophobic tails trap grease/oil, hydrophilic heads interact with water → micelle formation → emulsifies dirt.

Numericals

Numeric problems are not available for this chapter.

CBSE Grade 10

Find out free resources that you need.

Subjects we teach

“Arise, awake, and learn by approaching the excellent teachers”

Shiksha Marg 108 gives you all free resources to ensure you get the best results. Get ready for you ICSE and CBSE exams!.

Questions & Answers

CBSE - Grade - 10

Subject: Science

Chapter - 04 - Carbon and Its Compounds

Types of Questions

MCQ

Fill in the Blanks

Name the Following

Answer in One Word

CBSE - Grade 10 - Science

All Chapters

CBSE - Grade 10 - Mathematics

All Chapters

CBSE - Grade 10 - English - First Flights

All Chapters

CBSE - Grade 10 - English - Words and Expressions

All Chapters

CBSE - Grade 10 - English - Supplementary Reader - Footprints without Feet

All Chapters

CBSE - Grade 10 - History

All Chapters

CBSE - Grade 10 - Civics

All Chapters

CBSE - Grade 10 - Geography

All Chapters

CBSE - Grade 10 - Economics

All Chapters

CBSE Grade 10

Find the Odd Man Out

Match the Pair

Short Answer Questions

Puzzles

Difference Between:

Assertion and Reason

True or False

Long Answer Questions

Give Reasons

Arrange the Words

Case Studies

Numericals

CBSE Grade 10

Find out free resources that you need.

ICSE

Grade 8

Grade 9

Grade 10

Grade 8

Grade 9

Grade 10

Subjects we teach

Success is Our Culture

Useful Links

Free Resources

True Knowledge is Divine