Question

The density of water is maximum at $4^\circ C$, what will happen if its density reduces on cooling?
A. Volume of water increases
B. Volume of water decreases
C. Volume of water first increase then decrease
D. Temperature of water remains same

Answer 1

We need to understand the concept of density and accordingly judge what will happen to water if the density reduces on cooling. Density is the mass of a material substance per unit volume. Density is calculated using the formula $d = \dfrac{M}{V}$, where d represents density, M is mass, and V is volume. The density of a substance is usually measured in grams per cubic centimetre. Water, for example, has a density of $1$ gramme per cubic centimetre, but the density of the Earth is $5.51$ grammes per cubic centimetre.

Complete answer:
Water behaves strangely because its density peaks at $4^\circ C$. Its density reduces as the temperature rises or falls over $4^\circ C$. Water, unlike other liquids, has a lower density and a higher volume when cooled from $4^\circ C$. As ice melts into liquid water, the density of the liquid rises, causing the structure to collapse. The molecules move faster and wider apart at temperatures much above freezing. As the temperature rises, the density drops. The water still has numerous ice-like clusters at temperatures approaching $0^\circ C$. Because these clusters are able to move about in relation to one another, water remains liquid. Because the clusters still have vacant areas, the liquid density decreases. The density of the liquid increases as the water molecules become closer together. The water molecules slow down and the density increases when the temperature of warm water drops. Clusters begin to develop at $4^\circ C$. The molecules are still slowing down and becoming closer together, while cluster formation pushes them further away. As a result of the larger influence of cluster formation, the density begins to drop. As a result, at $4^\circ C$, the density of water reaches its maximum.

So, the correct answer is “Option A”.

Note:
Note that water behaves strangely because its density peaks at $4^\circ C$. Its density reduces as the temperature rises or falls over $4^\circ C$. Water, unlike other liquids, has a lower density and a higher volume when cooled from $4^\circ C$.