Question

which of the following is a coloured gas?
A.\[N{O_2}\]
B.${N_2}{O_5}$
C.${N_2}{O_4}$
D.${N_2}O$

Answer 1

Hint:The only gas which is the coloured gas in the above options of gases also has a pungent odour, Its vapours are heavier than the air. It is used in the production of the fertilizers primarily. Also it smells similarly as chlorine.

Complete step by step answer:
In the question given above, we have four options. Let’s study all of them one by one to find out who among them is coloured.
Nitrogen dioxide \[N{O_2}\] : nitrogen dioxide appears as a brown coloured gas. It has a pungent odor Or smells like chlorine. It is used in the production of nitric acid as an intermediate, in producing chemical explosive, it is used as nitrating agent for, For Acrylates, it is used as inhibitor for polymerization, and also as an agent of flour bleaching.
Dinitrogen pent-oxide ${N_2}{O_5}$: it is also an anhydride form of nitric acid. It is odourless, and it appears in nature as a white crystal. It is soluble with alcohol and ether. Nitrogen penta-oxide is used in high fuel rockets as oxidizer, in modern synthetic chemistry it is used as an nitrating agent.
Dinitrogen tetroxide ${N_2}{O_4}$: also known as nitrogen tetroxide, appears as a reddish brown liquid, it has unpleasant odor, rather sharp, It has a low boiling point and remains as a liquid under compression. It is formed by the combination of two molecules of nitrogen dioxide. Now this nitrogen dioxide combines to form dinitrogen tetroxide. It forms a colourless gas.
Dinitrogen oxide ${N_2}O$ : it is observed as gas at room temperature, it is denser then air, it is a colourless gas, It is tasteless, odour is sweetish. Dinitrogen oxide is popularly known as laughing gas because if inhaled by someone, it causes them to laugh continuously without any reason.

Hence, option A is correct.

Note:
Now, the thing to remember is that increasing the level of nitrogen dioxide can cause a damaged human respiratory tract and causes an increased vulnerability, and respiratory infection or maybe asthma.