Question

how does the density of water change at temperatures below 4°? decreases increases

Explanation:

Water has a unique property. Its density is maximum at 4°C. Below 4°C, as temperature decreases, water molecules start to form more open - structured hydrogen - bonded networks, causing the volume to increase while mass remains constant. According to the density formula $
ho=\frac{m}{V}$, when $V$ increases and $m$ is constant, density decreases.

Answer:

Decreases