Question

Identify the gas evolved in the following reactions when:
Few crystals of $KN{O}_3$ are heated in a hard glass test tube.

Answer 1

The gas that evolved is Oxygen, $O_2$.
When crystals $KN{O}_3$are heated in a hard glass test tube, oxygen ($O_2$) gas is evolved.

$KN{O}_3\left(s\right)\stackrel{∆}{\to }KN{O}_2\left(s\right)+O_2\left(g\right)$

Potassium Nitrate Potassium Nitrite Oxygen
Oxygen $O_2$ is given off.