ICSE Class 7 Answered

Water shows unusual expansion when it is cooled from 4°C to 0°C. This property of water is termed as “anomalous expansion of water.”

All liquids expand on heating and contract on cooling. Water also contracts on cooling till it reaches a temperature of 4°C On cooling below 4°C, water expands instead of contracting. This unusual behavior of water is called anomalous expansion of water.

Therefore, the volume of water at 0°C  is more than volume of water at 4°C and the density of water at 0°C is less than volume of water at 4°C.