Class 10 Science

Carbon and Its Compounds NCERT Exemplar Problems

MCQ Part 2

Question 15: Ethanol reacts with sodium and forms two products. These are

  1. sodium ethanoate and hydrogen
  2. sodium ethanoate and oxygen
  3. sodium ethoxide and hydrogen
  4. sodium ethoxide and oxygen

    Answer: (a) Sodium ethanoate and hydrogen

    Explanation: The following equation shows this reaction:

    2Na + 2CH3CH2OH → 2CH3CH2Na + H2

Question 16: Vinegar is a solution of

  1. 50% – 60% acetic acid in alcohol
  2. 5% – 8% acetic acid in alcohol
  3. 5% – 8% acetic acid in water
  4. 50% – 60% acetic acid in water

    Answer: (c) 5% - 8% acetic acid in water

Question 17: Structural formula of benzene is

exemplar problems mcq options

Answer: (c)

Question 18: The correct structural formula of butanoic acid is

exemplar problems mcq options

Answer: (d)

Explanation: Butanoic acid is represented by the chemical formula C3H7COOH; which is shown in option ‘d’.

Question 19: Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of

  1. Helium
  2. Neon
  3. Argon
  4. Krypton

    Answer: (b) Neon

    Explanation: Neon is the nearest inert gas from carbon, and an element tries to attain the electronic configuration of its nearest noble gas while attaining a fully-filled outermost shell.

Question 20: Mineral acids are stronger acids than carboxylic acids because

  1. mineral acids are completely ionized
  2. carboxylic acids are completely ionized
  3. mineral acids are partially ionized
  4. carboxylic acids are partially ionized
  1. (i) and (iv)
  2. (ii) and (iii)
  3. (i) and (ii)
  4. (iii) and (iv)

    Answer: (a) (i) and (iv)

Question 21: The correct electron dot structure of a water molecule is

exemplar problems mcq options

Answer: (c)

Explanation: In this option, oxygen has a complete octet while each atom of hydrogen has two electrons in outermost shell.

Question 22: Which of the following is not a straight chain hydrocarbon?

exemplar problems mcq options

Answer: (d)

Question 23: Which among the following are unsaturated hydrocarbons?

exemplar problems mcq options
  1. (i) and (iii)
  2. (ii) and (iii)
  3. (ii) and (iv)
  4. (iii) and (iv)

    Answer: (c) (ii) and (iv)

    Explanation: These options show double bond and triple bond; hence these are unsaturated hydrocarbons.

Question 24: Which of the following does not belong to the same homologous series?

  1. CH4
  2. C2H6
  3. C3H8
  4. C4H8

    Answer: (d) C4H8

    Explanation: This option follows the generic formula CnH2n, while others follow the generic formula CnH2n+2.

Question 25: The name of the compound CH3 — CH2 — CHO is

  1. Propanal
  2. Propanone
  3. Ethanol
  4. Ethanal

    Answer: (d) Ethanal

    Explanation: The functional group – CHO means a suffix ‘al’ needs to be with the name of this compound. Moreover, presence of two atoms of carbon (apart from that in the functional group) means the name is derived from ethane.

Question 26: The heteroatoms present in CH3 — CH2 — O — CH2— CH2Cl are

  1. Oxygen
  2. Carbon
  3. Hydrogen
  4. Chlorine
  1. (i) and (ii)
  2. (ii) and (iii)
  3. (iii) and (iv)
  4. (i) and (iv)

    Answer: (d) (i) and (iv)

    Explanation: Any atom apart from carbon and hydrogen is called heteroatom.

Question 27: Which of the following represents saponification reaction?

  1. CH3COONa + NaOH + CaO → CH4 + Na2CO3
  2. CH3COOH + C2H5 + H2SO4 → CH3COOC2H5 + H2O
  3. 2CH3COOH + 2Na → 2CH3COONa + H2
  4. CH3COOC2H5 + NaOH → CH3COONa + C2H5OH

    Answer: (d)

    Explanation: In saponification reaction, ester is treated with an alkali to obtain sodium salt and alcohol.

Question 28: The first member of alkyne homologous series is

  1. Ethyne
  2. Ethene
  3. Propyne
  4. Methane

    Answer: (a) Ethyne