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CBSE · Class 10 · Science

Carbon and its Compounds

Standard difficulty · 20 questions · 40 marks

Name: Date: Score: ____ / 40

Show your working for Sections B and C. Answers are on the last page — try every question first!

Section A — Choose the correct answer8 × 1 = 8 marks
1.
The formula of propane is:
  1. C3H8
  2. C3H7Cl
  3. C2H6
  4. C2H5COOH
2.
The compound CH3CH2Cl belongs to the homologous series of:
  1. aldehydes
  2. carboxylic acids
  3. alkanes
  4. haloalkanes
3.
Carbon forms bonds mainly by:
  1. gaining electrons
  2. losing electrons
  3. sharing electrons (covalent bonds)
  4. forming ions
4.
The next higher homologue of propanoic acid (C2H5COOH) is:
  1. C3H7COOH
  2. C4H10
  3. C4H8
  4. C3H7CHO
5.
The molecular mass of heptene (C7H14) is: (C = 12 u, H = 1 u, O = 16 u, Cl = 35.5 u)
  1. 100 u
  2. 112 u
  3. 98 u
  4. 96 u
6.
How many covalent bonds are there in a molecule of pentane (C5H12)?
  1. 17
  2. 15
  3. 16
  4. 22
7.
Which of these will decolourise bromine water?
  1. C4H6
  2. C4H9Cl
  3. C4H10
  4. CH3Cl
8.
Assertion (A): C3H7OH and C5H11OH are successive members of the same homologous series.
Reason (R): Successive members of a homologous series differ by a CH2 unit.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
Section B — Short answer8 × 2 = 16 marks
9.
Write the name and formula of the fourth member of the aldehyde series.
10.
Write the balanced equation for the complete combustion of pentanol (C5H11OH).
11.
Find the molecular masses of chloromethane (CH3Cl) and chlorobutane (C4H9Cl). By how much do they differ? (C = 12 u, H = 1 u, O = 16 u, Cl = 35.5 u)
12.
Why can carbon form a very large number of compounds?
13.
Write the condensed structural formula of ethanol and name its functional group.
14.
For ethane (C2H6), how many C–H bonds and carbon–carbon bonds of each kind are there? How many covalent bonds (shared pairs) in all?
15.
Write the equation for the reaction of butane with chlorine in sunlight, when one hydrogen atom is replaced. Name the organic product.
16.
Name the compound CH3CH2OH, and write the formula and name of its next higher homologue.
Section C — Word problems4 × 4 = 16 marks
17.
A compound X (C2H4O2) turns blue litmus red and gives a gas with sodium carbonate that turns lime water milky. Identify X and write the equation.
18.
46 g of ethanol burns completely in oxygen. Write the balanced equation, and find the masses of oxygen used and of carbon dioxide and water formed. (Atomic masses: H = 1 u, C = 12 u, O = 16 u)
19.
An organic compound X has the molecular formula C5H8. It decolourises bromine water, and one molecule adds two molecules of hydrogen in the presence of nickel. Identify X and its homologous series, and write the name and formula of its next higher homologue.
20.
For the carboxylic acids: write the names and formulas of the members with 3, 4, 5 carbon atoms, the general formula of the series, and the difference in molecular mass between successive members.
AmbifulWorksheets
Practice that never repeats
CBSE · Class 10 · Science

Answer key

Carbon and its Compounds · AW-10S-CAR-2026-V1 · For parents — fold back or tear off before handing the sheet to your child.

QAnswerWorking
1(a) C3H8alkanes, 3 carbon atoms
2(d) haloalkanesfunctional group: –Cl (halo group)
3(c) sharing electrons (covalent bonds)—
4(a) C3H7COOHadd one CH2 unit
5(c) 98 u—
6(c) 164 C–C + 12 C–H
7(a) C4H6unsaturated compounds (C=C or C≡C) add bromine
8(d) A is false, but R is true.A is false: they differ by C2H4 (28 u), two CH2 units, so they are not successive. R is true.
9Butanal, C3H7CHOthe aldehydes start at 1 carbon atom
102C5H11OH + 15O2 → 10CO2 + 12H2Oproducts are carbon dioxide and water
1150.5 u and 92.5 u; they differ by 42 u3 CH2 units × 14 u
12Catenation: it links with other carbon atoms into chains, branches and rings. Tetravalency: it bonds with four other atoms, such as carbon, hydrogen, oxygen, nitrogen and chlorine.—
13CH3CH2OH; –OH (alcohol)—
14C–H: 6; C–C single: 1; 7 shared pairsa double bond is 2 shared pairs, a triple bond 3
15C4H10 + Cl2 → C4H9Cl + HCl; chlorobutanesubstitution: Cl replaces H
16Ethanol; next: C3H7OH, propanolalcohols; add CH2
17X is ethanoic acid: 2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2.—
18C2H5OH + 3O2 → 2CO2 + 3H2O; oxygen 96 g; carbon dioxide 88 g; water 54 gC2H5OH = 46 u; 1 mol; ratio 1 : 3 : 2 : 3
19X is pentyne (C5H8), one of the alkynes; next: hexyne, C6H10—
20propanoic acid C2H5COOH; butanoic acid C3H7COOH; pentanoic acid C4H9COOH; general formula CnH2nO2; 14 u (one CH2)—