Laughing gas is -
High-Yield Explanation
Ans. is 'a' i.e., N2OSpecial gaseso Sewer gas - H2S with CO2 and methane.o Marsh gas - Methaneo War gases :Tear gas - (i) Bromobenzylcyanide (BBC), (ii) Chloroacetophenone (CAP)Blister gas - Mustard gas and BAL (Lewisite) gasSickening gas - Diphinyl-amine-chlor-arsineLaughing gas - N2O