Question

What is meant by Anomalous expansion of water?
$(a)$ Water behaves like other liquid up to 4 degree centigrade. But below that temperature its density decreases till it is converted to ice.
$(b)$ Water behaves like other liquid up to 4 degree centigrade. But below that temperature its density increases till it is converted to ice.
$(c)$ Water behaves like other liquid up to 4 degree centigrade. But below that temperature its density remains constant till it is converted to ice.
$(d)$ None of these

Answer 1

Hint – There is a notable irregular maximum density pattern for water, it reaches a density peak at ${3.98}^0\text{C or 39}\text{.1}{\text{6}}^{0}F$. Use this concept to get the right option.

Complete step-by-step answer:
The anomalous expansion of water is an abnormal property of water whereby it expands instead of contracting when the temperature goes from 4°C to 0°C, and it becomes less dense. The density becomes less and less as it freezes because molecules of water normally form open crystal structures when in solid form.
Normally, liquids contract on cooling & the density increases. However, water is special. It contracts when cooled, down to a temperature of 4°C but thereafter begins to expand as it reaches 0°C and turns into ice.
So we see that the density decreases.

Hence option (A) is correct.

Note – This anomalous expansion of water is an abnormal property, and is accused by the hydrogen bonding between the oxygen atoms that are negatively charged and the hydrogen atoms that are positively charged, from two different molecules of water.