Question

When ice melts, its volume ______.
A) Increases
B) Decreases
C) Does not change
D) Can’t say

Answer 1

Hint: We need to understand the relation between the fusion of the ice or a solid into the liquid form and the temperature involved and therefore, the volume changes. These relations can help us understand the relation between melting and the change in volume.

Complete Solution:
Ice is the solid form of water. Usually, solids are characterised by the high-density molecular structure, whereas the liquids are having more intermolecular spacing. But the water is an exceptional case of a liquid, which is denser than its solid phase. i.e., the ice is less than water.
When the solid ice converts to the water form, the density increases. We know that the density of a material is inversely proportional to the volume of the material for a given mass.
i.e.,
\[\begin{align}
  & \text{Density}=\dfrac{\text{Mass}}{\text{Volume}} \\
 & \therefore \text{Density}\propto \dfrac{\text{1}}{\text{Volume}} \\
\end{align}\]
Now, we can see that as the density of the liquid water increases, the space occupied by the molecules of the water will be lesser than that of the solid ice. A denser medium occupies less space as compared to a less-denser medium. The spacing between the molecules in a substance determines its density. The lesser the density, the higher will be the volume occupied.
From these arguments, we can conclude that the volume occupied by water will decrease as the solid ice turns into liquid water.

The correct answer is option B.

Note:
The ice cubes consist of too many air gaps in its hexagonal structure. These air gaps constitute the major volume occupied by the ice in its solid form. When the ice melts, the air trapped in these gaps will escape, making the water molecules to come closer thus, making the water denser.