Class 10 NCERT Solution Carbon and its Compounds

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NCERT In-text Solved Questions

Question: 1. What would be the electron dot structure of carbon dioxide which has the formula CO2?

 of eight atoms of sulphur? (Hint – The eight atoms of sulphur are joined together in the form of a ring.)

Answer: 

Question: 3. How many structural isomers can you draw for pentane?

Answer: Pentane has three structural isomers. These are n-pentane, Iso-pentane and neo-pentane. Structures of all the three isomers are given here.

Question: 4. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us? 
Answer: Carbon can form a huge number of carbon compounds because of the following properties:

  1. Catenation: Carbon can form a bond with other carbon atoms. This property is called catenation. Because of catenation, carbon can form long chains, branched chains and closed chains.
  2. Carbon can form compounds with elements of many other elements.

Question: 5. What will be the formula and electron dot structure of cyclopentane?

Answer: Formula of cyclopentane is C5H10

Question: 6. Draw the structures for the following compounds.

  1. Ethanoic acid
  2. Bromopentane*
  3. Butanone
  4. Hexanal

Answer: 

Question: 7. Are structural isomers possible for bromopentane?

Answer: Yes, the isomer of bromopentane is possible. The structure of one of the isomers of bromopentane is given above.

Question: 8. What would you name the following compounds?

Answer:

(i) Bromoethane

Explanation: There is a Bromo group with two carbon atoms.

(ii) Methanal

Explanation: There is an aldehyde group in this compound with one carbon atom.

(iii) Hexyne

Explanation: There is a triple bond with six carbon atoms.

Question: 9. Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Answer: The conversion of ethanol to ethanoic acid is as follows:

CH3CH2OH + (Alkaline KMnO4 ) ⇨ CH3COOH

Since in this reaction one oxygen is added to ethanol, hence it is an oxidation reaction.

Question: 10. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Answer: When a mixture of oxygen and ethyne is burnt, it gives high temperature because of complete combustion and gives a clean flame. But when ethyne is burnt with air, it results in incomplete combustion. Incomplete combustion will not give a high temperature simultaneously it will give sooty flame. This is the reason, oxygen is used; instead of air; to burn ethyne.

Question: 11. How would you distinguish experimentally between alcohol and carboxylic acid?

Answer: When an acid reacts with carbonate and hydrogen carbonate, it gives carbon dioxide which turns lime water milky. On the other hand, alcohol does not give carbon dioxide on reaction with carbonate or hydrogen carbonate. Thus, the reaction with carbonate or hydrogen carbonate can be used to distinguish between carboxylic acid and alcohol.

Question: 12. What are oxidising agents?

Answer: Substances which give oxygen or replace hydrogen in reaction with other compounds are called oxidising agents, for example; potassium permanganate.

Question: 13. Would you be able to check if the water is hard by using a detergent?

Answer: Detergent gives lather with hard and soft water both, while a soap gives lather with soft water only. Thus, it is not possible to check if the water is hard; by using a detergent.

Question: 14. People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Answer: Molecules of soap form micelles with dirt, such as grease. Micelles remain suspended as a colloid. To remove dirt in the form of micelles from clothes agitation is necessary to get clean clothes.