The first member of the alkyne group of hydrocarbons is:

Correct option is D

The correct answer is (D) ethyne.

Explanation:
Ethyne (C₂H₂), also known as acetylene, is the first member of the alkyne group, which contains hydrocarbons with a triple bond.

Incorrect Options Explanations:

• (A) butyne: A four-carbon alkyne, not the first.
• (B) propyne: A three-carbon alkyne, not the first.
• (C) methyne: Does not exist, as a triple bond with one carbon is not possible.

Information Booster:

• Alkynes: Hydrocarbons with a triple bond.
• Ethyne (Acetylene): Used in welding, simplest alkyne.