Class 10 Science

Carbon and Its Compounds

NCERT Exemplar Problems

Part 1

Carbon exists in the atmosphere in the form of

  1. carbon monoxide only
  2. carbon monoxide in traces and carbon dioxide
  3. carbon dioxide only
  4. coal

    Answer: (c) Carbon dioxide only

    Explanation: Carbon monoxide is produced from volcanoes and from oxidation of petroleum products. However, carbon monoxide is short-lived and is eventually oxidized into carbon dioxide.

A molecule of ammonia (NH3) has

  1. only single bonds
  2. only double bonds
  3. only triple bonds
  4. two double bonds and one single bond

    Answer: (a) Only single bonds

    Explanation: Nitrogen’s valency is 3 and hence one atom of nitrogen combines with three atoms of hydrogen in a molecule of ammonia.

Which of the following statements are usually correct for carbon compounds? These

  1. are good conductors of electricity
  2. are poor conductors of electricity
  3. have strong forces of attraction between their molecules
  4. do not have strong forces of attraction between their molecules
  1. (i) and (iii)
  2. (ii) and (iii)
  3. (i) and (iv)
  4. (ii) and (iv)

    Answer: (d) (ii) and (iv)

    Explanation: Carbon compounds are bad conductors of electricity because of the presence of covalent bonds in them. Moreover, covalent bonds do not have strong forces of attraction.

Buckminsterfullerene is an allotropic form of

  1. Phosphorus
  2. Sulphur
  3. Carbon
  4. Tin

    Answer: (c) Carbon

Which of the following are correct structural isomers of butane?

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

    Answer: (c) (i) and (ii)

    Explanation: Butane is represented by the chemical formula C4H10. Structural formulae in other options show 8 atoms of hydrogen.

In the given reaction, alkaline KMnO4 acts as

CH3– CH2– OH + Alkaline KMnO4 + Heat → CH3 – COOH

  1. reducing agent
  2. oxidising agent
  3. catalyst
  4. dehydrating agent

    Answer: (b) Oxidising agent

    Explanation: In this reaction, oxygen is being added to ethanol; resulting in formation of ethanoic acid. This shows that alkaline KMnO4 is an oxidizing agent.

Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of

  1. Addition reaction
  2. Substitution reaction
  3. Displacement reaction
  4. Oxidation reaction

    Answer: (a) Addition reaction

    Explanation: In this reaction, oil is converted into fat because of addition of hydrogen atoms.

In which of the following compounds, — OH is the functional group?

  1. Butanone
  2. Butanol
  3. Butanoic acid
  4. Butanal

    Answer: (b) Butanol

    Explanation: The suffix ‘ol’ means – OH is the functional group.

The soap molecule has a

  1. hydrophilic head and a hydrophobic tail
  2. hydrophobic head and a hydrophilic tail
  3. hydrophobic head and a hydrophobic tail
  4. hydrophilic head and a hydrophilic tail

    Answer: (a) Hydrophilic head and a hydrophobic tail

    Explanation: The hydrophobic head of soap molecules traps grease, while hydrophilic tail bonds with water during micelle formation.

Which of the following is the correct representation of electron dot structure of nitrogen?

exemplar problems mcq options

Answer: Answer: (d)

Explanation: A careful counting shows that each atom of nitrogen gets a complete octet in this structure. This is not the case in other options.

Structural formula of ethyne is

exemplar problems mcq options

Answer: (a)

Explanation: Ethyne is represented by chemical formula C2H2 which is shown in option ‘a’.

Identify the unsaturated compounds from the following

  1. Propane
  2. Propene
  3. Propyne
  4. Chloropropane
  1. (i) and (ii)
  2. (ii) and (iv)
  3. (iii) and (iv)
  4. (ii) and (iii)

    Answer: (d) (ii) and (iii)

    Explanation: Suffixes ‘ene’ and ‘yne’ show that these are unsaturated compounds of carbon.

Chlorine reacts with saturated hydrocarbons at room temperature in the

  1. absence of sunlight
  2. presence of sunlight
  3. presence of water
  4. presence of hydrochloric acid

    Answer: (b) Presence of sunlight

    When chlorine reacts with saturated hydrocarbon at room temperature, it displaces hydrogen atoms one by one.

In the soap micelles

  1. the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster.
  2. ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster.
  3. both ionic end and carbon chain are in the interior of the cluster
  4. both ionic end and carbon chain are on the exterior of the cluster

    Answer: (a) The ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster

Pentane has the molecular formula C5H12. It has

  1. 5 covalent bonds
  2. 12 covalent bonds
  3. 16 covalent bonds
  4. 17 covalent bonds

    Answer: (c) 16 covalent bonds

    Explanation: Make the structural formula and count the number of bonds to solve this question.
structural formula of pentane