Multiple choice Which of the following group of gases have highest concentration in atmosphere? Oxygen and Hydrogen Hydrogen and Nitrogen Nitrogen and Oxygen Carbon dioxide and Hydrogen Carbon dioxide and water vapours Reveal answer Fill a bubble to check yourself C Correct answer Explanation Nitrogen and oxygen are the main components of the atmosphere by volume. Together these two gases make up approximately 99% of the dry atmosphere. But Nitrogen is present in the highest concentration(78.08%).