Question

Which change in state would involve a decrease in the intermolecular force of attraction holding the water particles together?

A) H2O(I) -> H2O(s)
B) H2O(g) -> H2O(I)
C) H2O(g) -> H2O(s)
D) H2O(s) -> H2O(I)

Answer 1

Answer: The correct option is D.

Explanation: There are 3 states of matter: Solid, Liquid and Gas.

• Solid state: In this state, the particles are closely held and hence, they have strong intermolecular forces of attraction.

• Liquid state: In this state, the particles are loosely held in comparison to the solid state and hence have weaker intermolecular forces of attraction as compared to the solid state.

• Gaseous state: In this state, the particles are very loosely held and they have the weakest forces of attraction amongst all the three states.

As we change the state from solid to liquid to gas, the particles are separated from each other and hence, the intermolecular forces of attraction will decrease.

Hence, from the given options, option D is the one in which the state changes from solid to liquid, so the particles are getting separated and therefore the intermolecular forces of attraction will decrease in this case.

Answer 2

When a substance present in it's gaseous state is cooled to liquid state, the particles present slow down and come close to each other as energy decreases. So the intermolecular forces increase as the particles come closer. Upon further cooling, particles present in the liquid state come more closer and change their phase to solid. Therefore, solids have the highest intermolecular forces and gases the least.

Therefore, the correct answer will be D) H2O(s) -> H2O(I) as on moving from solid to liquid state, the particles absorb energy and move apart from each other decreasing the intermolecular forces of attraction.