Which of the following is known as laughing gas?

Correct answer: (a) Nitrous Oxide

Explanation

Nitrous oxide (N₂O) is called laughing gas for its euphoric, intoxicating effect when inhaled.

It is a colourless, non-flammable gas first prepared by Joseph Priestley (1772) and used as a dental/medical anaesthetic and sedative.

CFCs, carbon monoxide and ammonia have no such laughing effect.