CBSE Class 10 Science – Chapter Wise Study Materials

Topic: Tetravalency, Bonding & Catenation (Q1–Q5)

1. Carbon is tetravalent because it has how many electrons in its outermost shell?

A) 2 B) 3 C) 4 D) 6

Answer: C) 4
Explanation: Carbon atom has electronic configuration 2,4 — four valence electrons allowing formation of four covalent bonds (tetravalency).
2. Which property of carbon explains its ability to form chains of carbon atoms?

A) Ionisation energy B) Catenation C) Electronegativity D) Atomic mass

Answer: B) Catenation
Explanation: Catenation is the ability of carbon to bond with other carbon atoms to form long chains and rings due to strong C–C bonds.
3. Which bond type is primarily responsible for holding atoms together in organic molecules?

A) Ionic bond B) Metallic bond C) Covalent bond D) Hydrogen bond

Answer: C) Covalent bond
Explanation: Organic molecules consist mainly of covalent bonds where electrons are shared between atoms (C–C, C–H, C–O etc.).
4. Which of the following explains why carbon forms a large number of compounds?

A) High atomic mass B) Small size and tetravalency C) Being a metal D) Low ionisation energy

Answer: B) Small size and tetravalency
Explanation: Carbon’s small size results in strong orbital overlap and its tetravalency enables multiple bonding patterns — both contributing to structural diversity.
5. The bond angle in methane (CH₄) is approximately:

A) 90° B) 109.5° C) 120° D) 180°

Answer: B) 109.5°
Explanation: Methane has tetrahedral geometry with bond angles of about 109.5°, due to sp³ hybridisation of carbon.

Topic: Homologous Series & Isomerism (Q6–Q12)

6. In a homologous series, successive members differ by which group?

A) CH B) CH₂ C) CH₃ D) C

Answer: B) CH₂
Explanation: Members of a homologous series differ by a CH₂ unit; this gives gradual change in physical properties.
7. Which of the following is an example of structural isomerism for C₄H₁₀?

A) Ethane and ethene B) n‑butane and isobutane C) Butane and butene D) Propane and propene

Answer: B) n‑butane and isobutane
Explanation: n‑Butane (straight chain) and isobutane (branched) are structural isomers with same molecular formula C₄H₁₀ but different connectivity.
8. The general formula of alkanes is:

A) CₙH₂ₙ B) CₙH₂ₙ₋₂ C) CₙH₂ₙ₊₂ D) CₙHₙ

Answer: C) CₙH₂ₙ₊₂
Explanation: Alkanes (saturated hydrocarbons) follow the general formula CₙH₂ₙ₊₂.
9. Cis‑trans isomerism is possible in which of the following?

A) Butane B) 2‑butene C) Butyne D) Butanol

Answer: B) 2‑butene
Explanation: 2‑Butene has a C=C double bond with different substituents on each carbon, allowing cis and trans forms (geometric isomerism).
10. Which statement about isomers is correct?

A) Isomers have different molecular formulas B) Isomers have same structural formula C) Isomers have same molecular formula but different structures D) Isomers always have identical properties

Answer: C) Isomers have same molecular formula but different structures
Explanation: Isomers share molecular formula but differ in atom connectivity or spatial arrangement, resulting in different properties.
11. Which of these is a secondary alcohol?

A) CH₃CH₂CH₂OH B) CH₃CH(OH)CH₃ C) CH₃OH D) (CH₃)₃COH

Answer: B) CH₃CH(OH)CH₃
Explanation: In CH₃CH(OH)CH₃ the carbon bearing —OH is attached to two other carbons — making it a secondary alcohol (propan‑2‑ol).
12. Which property typically changes gradually down a homologous series?

A) Chemical reactivity B) Physical properties like boiling point C) Functional group D) Molecular formula

Answer: B) Physical properties like boiling point
Explanation: Physical properties such as boiling point and melting point show a gradual change with increasing molecular size in a homologous series.

Topic: Nomenclature & Representative Compounds (Q13–Q17)

13. The IUPAC name of CH₃CH₂CH₂CH₃ is:

A) Butane B) 2‑Butene C) Butanol D) Methane

Answer: A) Butane
Explanation: CH₃CH₂CH₂CH₃ is a four‑carbon saturated chain — named butane as per IUPAC.
14. Which compound is named ethanol?

A) CH₄ B) CH₃CH₂OH C) CH₃COOH D) CH₃CHO

Answer: B) CH₃CH₂OH
Explanation: CH₃CH₂OH is the two‑carbon alcohol — ethanol.
15. CH₃COOH is commonly called:

A) Ethanol B) Ethanoic acid C) Acetone D) Ethanal

Answer: B) Ethanoic acid
Explanation: CH₃COOH is ethanoic acid (acetic acid), a carboxylic acid with formula CH₃COOH.
16. Which of these is ethyl ethanoate (an ester)?

A) CH₃COOCH₂CH₃ B) CH₃CH₂OH C) CH₃COOH D) CH₃CHO

Answer: A) CH₃COOCH₂CH₃
Explanation: CH₃COOCH₂CH₃ is the ester formed from ethanoic acid and ethanol (ethyl ethanoate).
17. The functional group —COOH is found in:

A) Alcohols B) Aldehydes C) Carboxylic acids D) Ketones

Answer: C) Carboxylic acids
Explanation: The —COOH (carboxyl) group defines carboxylic acids like ethanoic acid.

Topic: Alcohols — Properties & Reactions (Q18–Q25)

18. Which intermolecular force explains higher boiling points of ethanol compared to ethane?

A) Ionic bonding B) Hydrogen bonding C) Metallic bonding D) Dipole repulsion

Answer: B) Hydrogen bonding
Explanation: Ethanol has —OH groups that form hydrogen bonds with each other and with water, raising boiling point versus nonpolar ethane.
19. Oxidation of a primary alcohol yields which of the following on mild oxidation?

A) Ketone B) Aldehyde C) Ester D) Alkane

Answer: B) Aldehyde
Explanation: Mild oxidation converts primary alcohols to aldehydes; stronger oxidation can further produce carboxylic acids.
20. Which reagent can oxidise alcohols to acids in the lab?

A) NaCl B) K₂Cr₂O₇/H₂SO₄ C) NaOH D) H₂

Answer: B) K₂Cr₂O₇/H₂SO₄
Explanation: Acidified potassium dichromate is a common oxidising agent used to oxidise alcohols to aldehydes/acid depending on conditions.
21. Reaction of ethanol with sodium metal produces:

A) Sodium ethoxide and H₂ B) Sodium hydroxide C) Ethanal D) No reaction

Answer: A) Sodium ethoxide and H₂
Explanation: Alcohols react with active metals to form alkoxide salts and hydrogen gas (2ROH + 2Na → 2RONa + H₂).
22. Which of the following describes dehydration of alcohols?

A) Addition of water B) Removal of water to form alkenes C) Oxidation to acid D) Reaction with NaOH

Answer: B) Removal of water to form alkenes
Explanation: Dehydration of alcohols (often with acid catalyst) yields alkenes via elimination of water.
23. Which alcohol is most soluble in water?

A) Methanol B) Hexanol C) Octanol D) Nonanol

Answer: A) Methanol
Explanation: Short chain alcohols like methanol are highly soluble due to strong hydrogen bonding; longer chains reduce solubility because of hydrophobic tails.
24. Which statement about tertiary alcohols is true?

A) They easily oxidise to carboxylic acids B) They do not oxidise easily under mild conditions C) They are primary alcohols D) They form aldehydes on oxidation

Answer: B) They do not oxidise easily under mild conditions
Explanation: Tertiary alcohols lack an H on the carbon bearing —OH, making them resistant to oxidation unless harsh conditions cleave C–C bonds.
25. Which of the following is an alcohol functional group?

A) —COOH B) —OH C) —CHO D) —COOR

Answer: B) —OH
Explanation: —OH (hydroxyl) group characterises alcohols.

Topic: Carboxylic Acids — Properties & Reactions (Q26–Q31)

26. Carboxylic acids contain which functional group?

A) —OH B) —COOH C) —NH₂ D) —CHO

Answer: B) —COOH
Explanation: The carboxyl group —COOH defines carboxylic acids and imparts acidic properties.
27. Which of the following is a property of short‑chain carboxylic acids?

A) Insoluble in water B) Have fruity smells C) Are acidic and soluble in water D) Do not react with carbonates

Answer: C) Are acidic and soluble in water
Explanation: Short chain carboxylic acids are polar and can hydrogen bond with water, making them soluble; they also show acidic behaviour.
28. Which reaction shows a carboxylic acid reacting with an alcohol?

A) Esterification B) Saponification C) Hydrogenation D) Substitution

Answer: A) Esterification
Explanation: Esterification is the reaction of a carboxylic acid with an alcohol to form an ester and water, usually acid‑catalysed.
29. Which of the following neutralises ethanoic acid?

A) Dilute HCl B) Sodium bicarbonate C) Ethanol D) KMnO₄

Answer: B) Sodium bicarbonate
Explanation: Carbonates or bicarbonates neutralise carboxylic acids producing carbon dioxide (effervescence), water and salt.
30. Which statement about ethanoic acid is correct?

A) It is an alcohol B) It is commonly called acetic acid C) It is insoluble in water D) It cannot form esters

Answer: B) It is commonly called acetic acid
Explanation: Ethanoic acid is acetic acid; it is a carboxylic acid used in vinegar and can form esters.
31. Which reagent can be used to test for the acidic nature of a compound by effervescence?

A) NaCl B) NaHCO₃ C) C₂H₅OH D) H₂O

Answer: B) NaHCO₃
Explanation: Sodium bicarbonate reacts with acids to produce CO₂ gas; effervescence indicates presence of an acid (e.g., carboxylic acid).

Topic: Esters & Saponification (Q32–Q37)

32. Esterification produces which two types of products?

A) Alcohol and acid B) Ester and water C) Soap and glycerol D) CO₂ and H₂O

Answer: B) Ester and water
Explanation: Esterification of alcohol and carboxylic acid yields an ester and water (acid catalyst).
33. Which catalyst is commonly used in laboratory esterification?

A) Conc. H₂SO₄ B) NaOH C) NaCl D) AgNO₃

Answer: A) Conc. H₂SO₄
Explanation: Concentrated sulfuric acid protonates reactants and removes water, shifting equilibrium towards ester formation.
34. Saponification is the hydrolysis of esters under which conditions?

A) Acidic B) Neutral C) Basic D) None

Answer: C) Basic
Explanation: Saponification is alkaline hydrolysis (e.g., NaOH) of esters (fats/oils) forming glycerol and fatty acid salts (soap).
35. Which of these is a product of saponification?

A) Alcohol only B) Glycerol and soap C) Ester D) Alkane

Answer: B) Glycerol and soap
Explanation: Saponification converts triglycerides into glycerol and sodium/potassium salts of fatty acids (soap).
36. Ethyl ethanoate smells like:

A) Vinegar B) Fruity/pear-like C) Rotten eggs D) Odourless

Answer: B) Fruity/pear-like
Explanation: Many esters have pleasant fruity smells; ethyl ethanoate is commonly described as fruity/pear-like.
37. Which functional group is present in esters?

A) —OH B) —COOH C) —COO— D) —NH₂

Answer: C) —COO—
Explanation: Esters contain the —COO— linkage (R–COO–R'), characteristic of ester molecules.

Topic: Soaps, Detergents & Cleaning Action (Q38–Q41)

38. Soap molecules have which structural features?

A) Polar head and nonpolar tail B) Two polar heads C) Completely nonpolar D) Ionic head only

Answer: A) Polar head and nonpolar tail
Explanation: Soap molecules are amphiphilic — ionic (hydrophilic) head and long hydrocarbon (hydrophobic) tail enabling micelle formation and cleaning.
39. Why do soaps form scum in hard water?

A) Reaction with Cl⁻ B) Reaction with Ca²⁺/Mg²⁺ C) Evaporation D) Reaction with Na⁺

Answer: B) Reaction with Ca²⁺/Mg²⁺
Explanation: Soap anions react with Ca²⁺/Mg²⁺ to form insoluble calcium/magnesium salts (scum), reducing cleaning efficiency.
40. Detergents are preferred over soap because:

A) They are cheaper B) They form scum C) They work in hard water D) They are non‑polar

Answer: C) They work in hard water
Explanation: Detergents contain sulphonate/sulfate groups that stay soluble in hard water and avoid scum formation.
41. Micelles are formed when soap molecules are in water. Where are the hydrophobic tails located?

A) Outside the micelle B) Inside the micelle C) Randomly oriented D) Dissolved separately

Answer: B) Inside the micelle
Explanation: Hydrophobic tails orient inward away from water, trapping oils; hydrophilic heads face the aqueous environment.

Topic: Combustion, Oxidation & Practical Reactions (Q42–Q46)

42. Complete combustion of methane yields:

A) CO and H₂O B) CO₂ and H₂O C) C and H₂ D) CO₂ only

Answer: B) CO₂ and H₂O
Explanation: In presence of sufficient oxygen, methane combusts to CO₂ and H₂O releasing energy.
43. Carbon monoxide is dangerous because it:

A) Has a strong smell B) Binds haemoglobin reducing O₂ transport C) Is visible D) Is heavier than air

Answer: B) Binds haemoglobin reducing O₂ transport
Explanation: CO forms carboxyhemoglobin, impairing oxygen delivery and causing poisoning even at low concentrations.
44. Which of the following oxidising agents is used in laboratory oxidations of alcohols?

A) KMnO₄ B) NaCl C) NaHCO₃ D) C₆H₁₂

Answer: A) KMnO₄
Explanation: Potassium permanganate is a strong oxidising agent used to oxidise alcohols to aldehydes or acids depending on conditions.
45. Which statement is true about incomplete combustion?

A) Produces more energy than complete combustion B) Produces CO and soot C) Requires excess oxygen D) Only happens for liquids

Answer: B) Produces CO and soot
Explanation: Incomplete combustion due to limited oxygen yields carbon monoxide and carbon (soot), and is hazardous and inefficient.
46. Which product is formed by oxidation of ethanol with excess oxidant?

A) Ethanal B) Ethane C) Ethanoic acid D) Ethyl ethanoate

Answer: C) Ethanoic acid
Explanation: Under strong/prolonged oxidation, ethanol is oxidised fully to ethanoic acid (CH₃COOH).

Topic: Mixed & Application Questions (Q47–Q50)

47. Which compound will give a silver mirror with Tollens' reagent?

A) Propanone B) Propanal C) Propane D) Propanol

Answer: B) Propanal
Explanation: Aldehydes (like propanal) are easily oxidised and reduce Tollens' reagent to metallic silver; ketones (propanone) generally do not.
48. Which of the following is NOT a characteristic of homologous series?

A) Same functional group B) Same chemical properties C) Differ by CH₂ unit D) Identical physical properties

Answer: D) Identical physical properties
Explanation: Members of a homologous series have similar but not identical physical properties — they change gradually with molecular mass.
49. Which of these reactions is an example of addition reaction?

A) Hydrogenation of ethene B) Combustion of methane C) Esterification D) Saponification

Answer: A) Hydrogenation of ethene
Explanation: Addition reactions involve adding atoms across a double bond; hydrogenation converts C=C to C–C by adding H₂.
50. Which of the following statements is correct about detergents and the environment?

A) All detergents are biodegradable B) Some detergents can cause water pollution if not biodegradable C) Detergents never affect aquatic life D) Detergents always form scum

Answer: B) Some detergents can cause water pollution if not biodegradable
Explanation: Certain synthetic detergents persist in the environment and can harm aquatic ecosystems — biodegradable formulations are preferable.

Carbon and Its Compounds – MCQs with Answers and Explanations

Topic: Tetravalency, Bonding & Catenation (Q1–Q5)

Topic: Homologous Series & Isomerism (Q6–Q12)

Topic: Nomenclature & Representative Compounds (Q13–Q17)

Topic: Alcohols — Properties & Reactions (Q18–Q25)

Topic: Carboxylic Acids — Properties & Reactions (Q26–Q31)

Topic: Esters & Saponification (Q32–Q37)

Topic: Soaps, Detergents & Cleaning Action (Q38–Q41)

Topic: Combustion, Oxidation & Practical Reactions (Q42–Q46)

Topic: Mixed & Application Questions (Q47–Q50)

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