Question

Which of the following is a colourless odourless neutral gas which supports combustion but not combustible?
(A) Oxygen
(B)Nitrogen
(C) Hydrogen
(D) Carbon dioxide

Answer 1

Hint: As we know that combustion is basically the process where any substance generally reacts with oxygen and gives off heat and combustible or commonly called inflammable is a property of any substance which has the capability to catch fire and burn easily.

Complete answer: Actually all the above given options of gases are more or less colourless and odourless but oxygen is the only gas which is colourless and odourless neutral gas that supports combustion and we know that combustion is a chemical process where a substance reacts with oxygen. So we can easily make out that the oxygen supports combustion of any fuel or any substance but itself is not a combustible gas which can catch fire and easily burn.
We also know that Carbon dioxide is a colourless gas but it contains a slightly pungent smell and bitter taste and it does not burn or catch fire and also it does not support combustion. At room temperatures, it exists as a gas or solid but it is usually stored as a liquid.
Then we have nitrogen which is also a colourless odourless gas and it also does not react under normal conditions but it does not support combustion and is not at all combustible.
Lastly, the Hydrogen gas which is again colourless and odourless but it is highly combustible and it can easily displace oxygen leading to shortness of breath. Hence it is also incorrect.

Therefore, the correct answer is (A).

Note: Remember that oxygen gas is one of the essential gases for a living organism to survive and this gas is colourless, odourless as well as tasteless and is neutral in nature. It is taken up by animals which use it to convert into carbon dioxide which is taken up by plants to use it as a source of carbon and release oxygen which is taken up by humans.