Question

Which of the following is an example of molecular solid?
A. Zinc Sulphide
B. Magnesium Oxide
C. Dry ice
D. Diamond

Answer 1

A molecular solid is a solid which is made up of discrete molecules. The forces that bind the molecules together in molecular solids are van der waals forces, hydrogen bonding, halogen bonding, London dispersion forces and so on. They are held together by weak forces.

Complete answer:
In order to determine the compound which is an example of molecular solid we must know about the structure of compounds given in the option.
In the case of zinc sulphide,
It is a metal sulphide having crystalline structure. It is not an example of molecular solid. So, this is an incorrect option.
In the case of magnesium oxide,
Magnesium oxide is an ionic solid and that’s why it is not an example of molecular solid. So, this is an incorrect option.
In the case of dry ice,
In dry ice molecules of hydrogen and carbon are attached together by van der waal forces. So, this is an example of molecular solid.
In the case of diamond,
Diamond is a network structure. It is formed by catenation of carbon atoms and that’s why it forms a network like structure. So, this is an incorrect option.
So, dry ice is an example of molecular solid.

Hence, option C is correct.

Note:
The solid form of carbon dioxide is named as dry ice. It is generally used as a cooling agent. it is also used for dramatic effect in fog machines at the theatre. The temperature of dry ice is lower than the temperature of water ice and it does not leave any residue after use(other than incidental frost from moisture in the atmosphere). In the preservation of frozen foods dry ice is used in the case when mechanical cooling is unavailable.