1).'In vaporization when heat energy supplied increases the potential
energy of the molecules.As the result intermolecular forces of attraction decrease'

2).Also explain why increase in potential energy decrease in intermolecular forces attraction

1) Sorry, I can't get your question. Please type the question completely for better understanding.
2) When there is an increase in potential energy, particles of matter start moving faster. This makes the particles to move away from each other. Thus, there is a decline in the intermolecular forces.