Question

Why white fumes appear when HCl gas is exposed to air?

Answer 1

Hey there....!!

When hydrogen chloride gas is exposed to air,
it reacts with the atmospheric water vapour,
leading to the formation of hydrochloric acid
& thereby it gives white fumes.

Answer 2

when exposed to air, hcl gas condenses with moisture in the air to dense,white and vapours due to air contains oxygen.