Question

If water is converted into ice and maintained at \[{0^0}C\], which of the following statements is true for the molecules of the substance?
(A) Only kinetic energy decreases
(B) Only potential energy decreases
(C) Both the energy increases
(D) Potential energy increases and kinetic energy decreases

Answer 1

Hint We know that the potential energy of a system decreases with the state change \[gas - liquid - solid\]. It is also noted that ice has less potential energy. We will use this concept and select the most appropriate option.

Complete step by step answer
It is given in the question that water is converted into ice and maintained at \[{0^{\rm O}}C\] then we have to find the correct statement in the given options.
We know that kinetic energy is associated with flowing and moving objects whereas potential energy is associated with a static object. In our question, it is mentioned that water is converted into ice and maintained at \[{0^{\rm O}}C\]. It means it is stored and the energy associated with it will be potential- energy.
We also know that the potential energy of a system decreases with the state change \[gas - liquid - solid\]. As we know that solid has the least potential energy whereas gases have more potential energy. Even in our question, the static water is converted to ice It means when the water is converted into ice its potential energy decreases.

Therefore, Option b is the correct answer.

Additional information
If we compare the kinetic and potential energy of the water vapor, water and ice then water vapor has the most kinetic as well as potential energy as compared to water and ice. This is because the particle of water vapor is free to move and they can move more vigorously.
 \[gas > liquid > solid\]
Please note that kinetic energy is associated with moving objects whereas potential energy is associated with a static object.

Note
One can think that ice is solid; it means it has more stability thus, its potential energy will be greater than liquid and gas but this is a myth. In ice, the force of attraction between the molecules also increases which makes it stable but this reduces its potential as well as kinetic energy. Here we do not consider kinetic energy because the water is static and kinetic energy is associated with flowing water.