Question

Which of the following is the most poisonous gas?
A. CO
B. $C{{O}_{2}}$
C. C
D. $S{{O}_{2}}$

Answer 1

Hint: Air pollution can cause the release of many toxic gases that can be very harmful to the environment and in some cases even life threatening.

Complete Answer:
Now, let us analyze each option to find the correct answer.
Option A: CO or carbon monoxide is considered to be the most toxic gas as it shows high affinity to haemoglobin. Carbon monoxide combines with haemoglobin to form carboxyhemoglobin that causes trouble in breathing and can lead to death by suffocation. Therefore, this option is correct.

Option B: The excess amount of carbon dioxide ($C{{O}_{2}}$) in the atmosphere can cause heating up of the earth surface which is also known as the Greenhouse effect. Excess of carbon dioxide can also cause headaches, dizziness and restlessness. It is not as toxic as carbon monoxide. Therefore, this option is incorrect.

Option C: Carbon as a single does not cause any harmful effect on the environment. In fact, it is a component of all living organisms and organic compounds. However burning of carbon like coal causes emission of carbon monoxide which is a toxic compound. But carbon itself is not a toxic compound let alone. Therefore, this option is incorrect.

Option D: Sulphur dioxide ($S{{O}_{2}}$) is an air pollutant which causes asthma, bronchitis, lung irritation and other problems. It is also a component of acid rain that corrodes buildings and other infrastructure. However, it is not as toxic as carbon monoxide. Therefore, this option is incorrect.

So, we can say that option A) CO (carbon monoxide) is the correct option.

Note: Air pollution is the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are different types of air pollutants, such as gases, particulates, and biological molecules.
Some of the air pollutants that can be harmful to human beings are listed below:
Carbon Monoxide, Sulphur Dioxide, Nitrogen Oxide, Tropospheric Ozone $({{O}_{3}})$ , Benzo(a)pyrene (BaP) and Particulate matter (PM).