Question

Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen can take place. Stating the essential conditions required for an addition reaction to occur, write the chemical equation giving the name of the reactant and the product of such a reaction.

Answer 1

There are two families of hydrocarbon which undergo addition reaction-

1. Alkenes : general formula- CnH2n

2. Alkynes: general formula- CnH2n-2

The condition is - the compound whose addition is to be done must be unsaturated i.e. have double or triple bond.

Examples-

1. C2H4 + H2 ---------- C2H6

Ethene Hydrogen Ethane

2. C2H2 + H2 ------- C2H4 + H2 ----------- C2H6

Ethyne Hydrogen Ehtne Hydrogen Ehtane

The product of the addition reaction is always saturated and one of the reactants are always unsaturated.







another answer
But their are formatting errors.
The name of the hydrocarbons that undergo addition reactions with H2 is:
1)Alkene: 
General Formula: CnH2n
2)Alkyne
General formula: CnH2n-2
The essential condition for addition reaction is : The hydrocarbon molecule must contain double or triple bond. For example
Reaction of alkene:
Addition of hydrogen to Ethene produce Ethane which is an alkane.
Reaction of alkyne:
Addition of Hydrogen to Ethyne also produce Ethane (alkane). But the difference is it requires two moles of H2

bonds can be shown like this

you should see the image above