Question

Give reason why do we see bubbles when water is heated

Answer 1

When water is heated, the flow of heat is by convection.

At 373.15K or 100°C, the water begins to get converted to steam, which is a gas. The water at the base of the container first forms steam, and by convection current, water at the top starts coming down and the newly formed steam starts to come at the top. While the steam us coming up, we see it enclosed in a bubble.