Which among the following gases is also known as ‘Laughing Gas’?

Nitrogen oxide

The correct answer is option 4. Nitrogen oxide.

The gas commonly known as "Laughing Gas" is nitrous oxide \((N_2O)\), which is option 4. Nitrous oxide is often used as an anesthetic in dentistry and surgery due to its analgesic (pain-relieving) and euphoric effects when inhaled in small doses. It gained the nickname "Laughing Gas" because of the euphoria or laughter some individuals experience after inhaling it.

Carbon monoxide (option 1), sulfur dioxide (option 2), and carbon dioxide (option 3) are not commonly referred to as "Laughing Gas." Carbon monoxide is a poisonous gas, sulfur dioxide is a pungent gas often associated with the smell of rotten eggs, and carbon dioxide is a naturally occurring gas essential for plant life but can be harmful in high concentrations.