Question

Helium is filled in weather balloons, because it is
a) non-inflammableb) less reactivec) condenses at very low temperatured) heavier than hydrogen

Answer 1

Hydrogen gas and normal air can ignite at as low as 4% air due to the oxygen.

Hydrogen is non flammable and non reactive as well as light.

Helium gas is employed for filling balloon because, it is inert gas and not flammable.

Hydrogen is even less denser than helium but hydrogen is flammable.

So, option a is correct.

Hope it helps! :)