Name two metals that start floating after some time when immersed in water and explain why they do so?
Calcium and magnesium are two metals that start floating after some time when immersed in water.
Explanation: Calcium and Magnesium react with water to form respective hydroxides and release hydrogen gas. The reactions are given as:
Ca + 2H2O → Ca(OH)2 + H2
Mg + 2H2O → Mg(OH)2 + H2
The bubbles of the hydrogen gas so formed in the reaction stick to the surface of the metal surface, and thus the metals float on water.