Question

How does the density of a liquid (or gas) vary with temperature?

Answer 1

Most of the liquids increase in volume with an increase in temperature, but water shows anomalous behaviour. Water has a maximum volume at 4°C and a maximum density at 4°C.
Actually, when volume increases, density decreases and when volume decreases, density increases.
But water, when cooled from high temperature, contracts up to 4°C because volume decreases and expands when cooled further below 4°C and hence the density of water increases when it is cooled up to 4°C while decreases when cooled further below 4°C. In other words, the density of water is maximum at 4°C equal to 1 g/cm³ or 1000 kg/m³.