નીચેનામાંથી કઈ ગેસ રંગહીન અને ગંધહીન નથી? A. નાઇટ્રોજન B. ક્લોરીન C. હાઇડ્રોજન D. ઓક્સિજન

Nitrogen, hydrogen and oxygen are all colourless and odourless gases. Chlorine is the exception: it is a greenish-yellow gas with a sharp, pungent, choking smell (the smell noticed near bleach or swimming pools). So chlorine is the gas that is not colourless and odourless.