Question

When Sunitha added a sodium piece to water in a laboratory, Hydrogen gas liberates
and catches fire but when she added calcium piece to water and that also liberates
hydrogen but does not catches fire. Will you inform her. Why?

Answer 1

Because Sodium is an explosive metal

Answer 2

A heat is produced during the reaction between sodium and water this makes the hydrogen burn..But the heat produced during the reaction between calcium and water release less heat .So the heat produced will attach the hydrogen gas to the surface of calcium due to which it floats on water

Hope this would help you..