Maximum contribution to atomospheric air is-

Ans. is 'a' i.e., N2 * The constituents of air:-# Major - Nitrogen (N2) - 78.1 %, Oxygen (O2) - 20.93%, Carbon dioxide (CO2) - 0.03%# Minor - Argon, neon, krypton, xenon, helium, water vapour, traces fo ammonia, suspended matter (dust, bacteria, spores, vegetable debris).