NCERT Class X Science Class: Chapter – 4. Carbon and Its Compounds – Part-15 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 56:

Explain the given reactions with the examples

  1. Hydrogenation reaction
  2. Oxidation reaction
  3. Substitution reaction
  4. Saponification reaction
  5. Combustion reaction


(a) Unsaturated hydrocarbons add hydrogen in the presence of nickel catalyst to give saturated hydrocarbons.

Image Unstaturated Hydrocarbons

(b) Ethanol is oxidized to ethanoic acid in the presence of alkaline on heating.

(c) In the presence of sunlight, chlorine is added to hydrocarbons.

(d) +

Used in the preparation of soap

(e) Most carbon compounds release a large amount of heat and light on burning

Question 57:

An organic compound A on heating with concentrated forms a compound B which on addition of one mole of hydrogen in presence of forms a compound C. One mole of compound C on combustion forms two moles of and 3 moles of . Identify the compounds A, B and C and write the chemical equations of the reactions involved.


Since compound C gives 2 moles of and 3 moles of , it shows that it has the molecular formula (Ethane) . C is obtained by the addition of one mole of hydrogen to compound B so the molecular formula of B should be (Ethene) . Compound B is obtained by heating compound A with concentrated which shows it to be an alcohol. So compound A could be (Ethanol)