Here's why:

* Metal + Water → Metal Hydroxide + Hydrogen Gas

This reaction involves a metal (typically an alkali metal or alkaline earth metal) reacting with water.

* The metal displaces the hydrogen from the water molecule.

* The metal forms a metal hydroxide, and hydrogen gas is released.

Example:

Sodium (Na) reacting with water (H₂O) produces sodium hydroxide (NaOH) and hydrogen gas (H₂).

Na + H₂O → NaOH + H₂

In this example, sodium (Na) displaces hydrogen (H) from water, resulting in the formation of sodium hydroxide (NaOH) and the release of hydrogen gas (H₂).