Question

Which compound is an alkyne?
(1) C2H2 (3) C4H8
(2) C2H4 (4) C4H10

Answer 1

the answer is C2H2 because an alkyne compound consists of a series of unsaturated hydrocarbons with a triple bond. 

Answer 2

Answer: $C_2H_2$

Explanation:

Saturated hydrocarbons are defined as the hydrocarbons in which a single bond is present between carbon and carbon atoms. The general formula for these hydrocarbons is $C_nH_{2n+2}$ and are called as alkanes.

Unsaturated hydrocarbons are defined as the hydrocarbons which have double or triple covalent C-C bonds. They are known as alkenes and alkynes respectively. The general formula for these hydrocarbons is $C_nH_{2n}$ and $C_nH_{2n-2}$ respectively.

$C_4H_8$ and $C_2H_4$ are alkenes.

$C_4H_{10}$ is an alkane.

Thus $C_2H_2$ with general formula $C_nH_{2n-2}$ is an alkyne.