When a gas jar full of air is placed upside down on a gas jar full of bromine vapours, the red-brown vapour of bromine from the lower jar go upward into the jar containing air. In this experiment:

(a) Air is heavier than bromine

(b) Both air and bromine have the same density

(c) Bromine is heavier than air

(d) Bromine cannot be heavier than air because it is going upward against gravity.