Question

Assertion: Carbon dioxide is used in fire extinguishers.

Reason: Carbon dioxide is a colourless and odourless gas.

Answer 1

Carbon dioxide $\left(C{O}_2\right)$ is denser than oxygen. When a fire breaks out, it settles over the burning object and forms an air blanket which cuts off the oxygen supply to the burning object. Therefore, it does not support combustion. Hence, it is ideal to use in fire extinguishers.

The reason given is correct as $C{O}_2$ is a colourless and odourless gas. However, being colourless or odourless does not help in extinguishing a fire.

Therefore, both assertion and reason are true but the reason is not the correct explanation for the assertion.