Question

When a kettle is placed on the stove and water begins to boil, the hotter water at the bottom begins to rise and the cooler water above it begins to sink. What do we know about the relationship between the hotter water and the cooler water?

Answer 1

The hotter water is less dense and rises. The cooler water then sinks because it is more dense.

Answer 2

Answer:

Hotter water is less dense than cooler water.

Explanation:

When we increase the temperature of water (we are not talking about ice and water as the density of water increases from 273.15K to 277.15 K, and then start decreasing) its density decreases due to more inter-molecular spaces between the molecules. With increase in temperature the kinetic energy of molecules increases which increases space and thus density decreases (volume increases).

Thus hotter water is less dense and rise up while cooler water is more dense and sinks down.