CBSE Class 10 Answered

(a) Molecular formula: CH₃-CH₂-OH and name: Ethanol.

           When it is heated with an excess of conc. Sulphuric acid elimination of water molecule takes place to give ethane.

(b) Substitution Reaction

• The reaction in which one or more hydrogen atoms of a hydrocarbon are replaced by some other atoms is called a substitution reaction.
• Substitution reactions are a characteristic property of saturated hydrocarbons.

For example:

1) Methane reacts with chlorine in the presence of sunlight to form chloromethane and hydrogen chloride.

  2)  When ethyl chloride is treated with alco.KOH it gives ethyl alcohol.