State and explain the anomalous expansion of water.

Explanation

In general, solids possess greater densities than liquids. Therefore, for such liquids, the density decreases with an increase in temperature as the liquids expand on heating. However, in the case of water it is different. Ice has lower density than water at the same temperature. As ice gets converted to water at `0^(@)C`, its density increases and this trend continues till the temperature rises to `4^(@)C`. Beyond `4^(@)C`, water shows normal trend of decrease in density with increase in temperature. Therefore, density of water is maximum at `4^(@)C` (1 g/cc). From 4 to `0^(@)C`, water undergoes expansion while all other liquids undergo contraction. Since this trend is opposite to the normal trend, this is called anomalous expansion of water.