Question

she observed that tiny bubbles appeared before the water starts to boil.she boiled the water for about 5 minutes and filled it in a bottle up to the brim and ket bottle air tight till it cooled down to room temperature why did the tiny bubbles appeared?

Answer 1

it shows the convectional method of heat transfer. the water that has been kept on stove bcomes hot and rises up while cool water on the surface comes down. when the water rises up she can see the bubbles that is the movement of water rising up.
hope it helps.....