Question

When heat energy is supplied to the substance, kinetic energy of its molecules:
A. Increases
B. Decreases
C. Remains same
D. Cannot be predicted

Answer 1

Hint: We know that energy is the ability to do work. The measure of energy is done by using the unit Joule. Energy is very essential for all living organisms. The primary source of energy on Earth is the Sun.

Complete step by step answer:
Two main categories of energy are kinetic energy and potential energy.
Let's discuss kinetic energy in detail. The energy which is in association of motion of an object is termed as kinetic energy. The formula of kinetic energy is,

Kinetic energy = $\dfrac{1}{2}m{v^2}$

Where, m is mass and v is velocity of the object.Now, come to the question. When heat energy is supplied to a substance, kinetic energy of the molecules increases due to which their movement increases.

So, the correct answer is Option A.

Additional Information:
Supplying heat energy also causes change of state of a substance. When supplying heat to a substance, the kinetic energy of the molecules increases. This overcomes the intermolecular force of attraction between molecules and molecules are free to move. Let's take the example of ice. Ice when heated is converted to liquid. This is because the intermolecular force of attraction between water molecules is weakened due to increasing kinetic energy of the molecules.
The energy stored in a stationary object is termed as potential energy. The formula of potential energy is,
Potential energy = $m \times g \times h$

Where, m is mass, h is height and g is gravitational field.

Note: According to the law of conservation of energy, total energy of a closed system is conserved, that means, neither creation nor destruction of energy is possible. But, there is a possibility of conversion of energy in various forms.