Answer:
Molecules are speeding up during boiling
Step-by-step explanation:
According to the kinetic theory of matter, matter exists in three states; solid, liquid and gas. In the solid state, the molecules of a substance are in fixed positions, the can only vibrate but can not translate. In the liquid state, the molecules acquire a greater degree of freedom and can translate in addition to vibration and rotation. In a gas the molecules are infinitely free and translate at high velocities.
Arrow 1 shows a phase change from liquid to gas. This occurs during boiling. This phase change is possible because the liquid molecules acquire energy in the form of heat supplied during boiling thereby making the molecules of the liquid to speed up their motion and escape the liquid surface as vapour.