Question

Arrange the following changes of energy during the following phase transition in proper order. Ice(0⁰C)$\to$Water(50⁰C)$\to$Ice(0⁰C)

(1) Potential energy increases and kinetic energy remains constant

(2) Potential energy decreases and kinetic remains constant

(3) Potential energy increases and kinetic energy increases

(4) Potential energy decreases and kinetic energy decreases

• A. 4 2 3 1
• B. 1 3 2 4
• C. 1 3 4 2
• D. 3 4 2 1

Answer 1

The correct option is C

1 3 4 2

Kinetic energy: It is defined as the energy which a body possesses by virtue of being in motion.

Potential energy: It is defined as the energy which a body has by virtue of its position.

(1) Potential energy increases, and kinetic energy remains constant

• At 0⁰C ice will convert into water by absorbing heat from the environment. This will change only the potential energy of the ice.
• At 0⁰C all the heat provided by the environment is used in breaking the strong bonds of solid and kinetic energy will not change.
• Therefore, only potential energy will change and kinetic energy remain constant.

(3) Potential energy increases, and kinetic energy increases

• After all the ice is melted into water, external heat is provided (0⁰C-50⁰C) which will increase the kinetic energy as well as the potential energy of water molecules.

(4) Potential energy decreases, and kinetic energy decreases

• When heat is decreasing (50⁰C-0⁰C) both potential and kinetic energy will start decreasing.

(2) Only the potential energy will change and kinetic will remain constant.

• When heat is removed and the water is placed at 0⁰C, it will freeze.
• The provided heat will help in converting the water into ice by increasing the strong forces between water molecules.

Therefore, the order is 1 3 4 2 hence option (c) is the correct.