Which of the following is represented in the highest percentage by volume in dry air?
a. carbon dioxide
b. oxygen
c. hydrogen
d. nitrogen

The correct answer is Option d.

Explanation:

Dry air is composed of a mixture of gases like argon, oxygen, nitrogen, carbon dioxide and many other gases present in trace amount.

The percentage of these gases by volume in dry air is:

Carbon dioxide = 0.03%

Argon = 0.93%

Oxygen = 20.95%

Nitrogen = 78.09%

Hydrogen = Trace amounts

From the above percentage values, we can easily say that nitrogen has the highest percentage by volume in dry air. Hence, the correct option is d.