Answer:

Explanation:
When heat is supplied to molecules, their kinetic energy increases.

Kinetic Energy:
- Kinetic energy refers to the energy of motion.
- It is the energy possessed by an object due to its motion.
- The faster an object moves, the more kinetic energy it has.

Heat and Kinetic Energy:
- Heat is a form of energy that can be transferred from one object to another due to a temperature difference.
- When heat is added to a substance, its internal energy increases.
- This increase in internal energy leads to an increase in the kinetic energy of the molecules.

Effect of Heat on Molecules:
- Molecules are constantly in motion, vibrating and moving around.
- When heat is supplied to molecules, it causes an increase in their kinetic energy.
- This increase in kinetic energy results in an increase in the speed and motion of the molecules.
- As the molecules move faster, they collide more frequently and with greater force.

Examples:
- Consider a solid substance, such as ice. When heat is applied to the ice, its molecules gain kinetic energy and start moving faster.
- As the kinetic energy increases, the ice melts into liquid water, where the molecules have even higher kinetic energy.
- If more heat is supplied, the water molecules gain even more kinetic energy and eventually turn into water vapor, which is a gas.

Conclusion:
When heat is supplied to molecules, their kinetic energy increases. This increase in kinetic energy leads to an increase in the speed and motion of the molecules.