On compression will the potential energy of the molecular of a solid increase ? Give reasons for your answer.

Arrange the following in the decreasing order (most important first ) of their importance, for the welfare of human society. Give reasons for your answer. Biogas, Citric acid, Penicillin Curd.

Two protons are brought towards each other. Will the potential energy of the system decrease or increase ? If a proton and an electron be brought nearer, then ?

Give two examples of molecular solid.

Are the bond energies of all the four C-H bonds in methane molecule equal ? Justify your answer.

A body thrown vertically upwards reaches a height of 30m in 4 seconds. Does it cover the first half of its journey in 2 seconds ? Give reason for your answer

Give reason for internal energy of a gas.