Carbon exists in the atmosphere in the form of(a) carbon monoxide only(b) carbon monoxide in traces and carbon dioxide(c) carbon dioxide only(d) coal

The correct answer is (b) carbon monoxide in traces and carbon dioxide.

Here's why:

1. Carbon exists in the atmosphere in several forms, not just one.

2. Carbon monoxide (CO) is indeed present in the atmosphere, but only in trace amounts. It is primarily produced from car exhaust and other types of combustion.

3. Carbon dioxide (CO2), on the other hand, is a major component of the atmosphere. It is released through natural processes such as respiration and volcano eruptions, and through human activities such as deforestation and burning fossil fuels.

4. Coal is a solid form of carbon and does not exist in the atmosphere.

So, while both carbon monoxide and carbon dioxide are present in the atmosphere, carbon monoxide is only there in trace amounts, making option (b) the correct answer.