Question

Among the following substances the lowest vapour pressure is exerted by:
A.Water
B.Alcohol
C.Ether
D.Mercury

Answer 1

Hint:Vapour pressure is depending upon the molecules that bond well and the forces of attraction of mercury metal atoms are quite strong. So, with the help of this relation we are able to find the lowest vapour pressure.

Complete step by step answer:

Vapour pressure can be explained as the pressure exerted by the gaseous form of liquid on the liquid itself when both are in equilibrium or in other words we can say that it is the ability of a compound to bond with itself.
Compound molecules that bond well with each other will have low vapour pressure whereas, poorly bonded compounds will have high vapour pressure.
The temperature at which the vapour pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is known as boiling point of the liquid.
There are three common factors which influence the vapour pressure are surface area, intermolecular forces and temperature. At different temperatures, different molecules have different vapour pressure. Vapour pressure increases with increase in temperature
The forces between the individual metal atoms of mercury is quite strong as compared to the cohesive molecular forces such as hydrogen bonding which is being present in case of alcohols, ethers and water.
Therefore, the option D is correct.
Mercury exerts the lower vapour pressure because of the strong bond among its atom.

Note:
At room temperature, the substance with lowest boiling point will have the highest vapour pressure and the substance with highest boiling point will have the lowest vapour pressure. Vapour pressure is the liquid property related to evaporation.