Carbon and Its Compounds NCERT Exemplar Problems
MCQ Part 1
Question 1: Carbon exists in the atmosphere in the form of
- carbon monoxide only
- carbon monoxide in traces and carbon dioxide
- carbon dioxide only
- 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.
Question 2: A molecule of ammonia (NH3) has
- only single bonds
- only double bonds
- only triple bonds
- 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.
Question 3: Which of the following statements are usually correct for carbon compounds? These
- are good conductors of electricity
- are poor conductors of electricity
- have strong forces of attraction between their molecules
- do not have strong forces of attraction between their molecules
- (i) and (iii)
- (ii) and (iii)
- (i) and (iv)
- (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.
Question 4: Buckminsterfullerene is an allotropic form of
- Phosphorus
- Sulphur
- Carbon
- Tin
Answer: (c) Carbon
Question 5: Which of the following are correct structural isomers of butane?
- (i) and (iii)
- (ii) and (iv)
- (i) and (ii)
- (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.
Question 6: In the given reaction, alkaline KMnO4 acts as
CH3– CH2– OH + Alkaline KMnO4 + Heat → CH3 – COOH
- reducing agent
- oxidising agent
- catalyst
- 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.
Question 7: Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of
- Addition reaction
- Substitution reaction
- Displacement reaction
- Oxidation reaction
Answer: (a) Addition reaction
Explanation: In this reaction, oil is converted into fat because of addition of hydrogen atoms.
Question 8: In which of the following compounds, — OH is the functional group?
- Butanone
- Butanol
- Butanoic acid
- Butanal
Answer: (b) Butanol
Explanation: The suffix ‘ol’ means – OH is the functional group.
Question 9: The soap molecule has a
- hydrophilic head and a hydrophobic tail
- hydrophobic head and a hydrophilic tail
- hydrophobic head and a hydrophobic tail
- 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.
Question 10: Which of the following is the correct representation of electron dot structure of nitrogen?
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.
Question 11: Structural formula of ethyne is
Answer: (a)
Explanation: Ethyne is represented by chemical formula C2H2 which is shown in option ‘a’.
Identify the unsaturated compounds from the following
- Propane
- Propene
- Propyne
- Chloropropane
- (i) and (ii)
- (ii) and (iv)
- (iii) and (iv)
- (ii) and (iii)
Answer: (d) (ii) and (iii)
Explanation: Suffixes ‘ene’ and ‘yne’ show that these are unsaturated compounds of carbon.
Question 12: Chlorine reacts with saturated hydrocarbons at room temperature in the
- absence of sunlight
- presence of sunlight
- presence of water
- 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.
Question 13: In the soap micelles
- the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster.
- ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster.
- both ionic end and carbon chain are in the interior of the cluster
- 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
Question 14: Pentane has the molecular formula C5H12. It has
- 5 covalent bonds
- 12 covalent bonds
- 16 covalent bonds
- 17 covalent bonds
Answer: (c) 16 covalent bonds
Explanation: Make the structural formula and count the number of bonds to solve this question.