Solve these questions plz

For the First answer I cant answer it But I can help you :  

The solid has constituent particles tightly packed and the lattice vibrations are carried out by them in their fixed position however oscillations take place about their mean position. These vibrations are increased as soon as there is increase in the temperature which eventually leads to the more chaotic motion of the constituents. At a fixed critical point of temperature, the bonds are broken and the constituent particles are spaced apart changing their phase into liquid. When more temperature is increased by gaining heat energy then the liquid changes into gas where the motion of constituent particles moving freely is dominant.

Explanation: