Question

a beaker of water turns hot when a grain of sodium is added to it. give reasons​

Answer 1

When sodium is dropped into the water it reacts with water very fast which is called exothermic reaction .so the beaker becomes hot ..

$\boxed{\sf {Na\atop Sodium}+{H_2O\atop Water}\longrightarrow {NaOH\atop Sodium\:Hydroxide}+Heat}$

Exothermic Reaction:-

The reaction which produces heat is called Exothermic reaction.

Ex:-

When Potassium or sodium reacts with water.

Answer 2

Answer:

a beaker of water turn hot when a grain off sodium is added to it