Question

Why does mercury not vaporizes in vacuum and water vaporizes in vacuum?.

Answer 1

Any liquid vaporize when they break apart their intermolecular forces and free themselves up.
Pressure of the surroundings acts as a hinderance to vaporization. As these oppose the ability of the gas molecules to vaporize.
At vacum gas pressure is zero and it will easily vaporize.
On the other hand mercury is a metal. Molecules of mercury are strongly bonded to one another. It requires very high temperature to vaporize. Mercury at high temperatures in vacum WILL vaporize. Under normal temperature conditions only water will vaporize