Question

which gas has highest partial pressure in the atmosphere?

Answer 1

Partial pressure of a gas is given by
p=Pxmolefraction.

Since the mole fraction of nitrogen is the highest in atmosphere, and partial pressure is directly proportional to mile fraction, Nitrogen will have the highest partial pressure.

Answer 2

In case of atmosphere, nitrogen has the highest concentration and therefore, the nitrogen will exert the maximum partial pressure.  

Explanation:

Partial pressure is exerted by each of the constituent elements in a gas mixture. Partial pressure of a gas exerted in a mixture would be the same as the gas would exert if it alone were to occupy the complete volume of the mixture at the same temperature. In atmosphere, we know that the gases are nitrogen, oxygen, water vapour, carbon dioxide and other gases. Of these, nitrogen constitutes 78% of the gaseous mixture. Partial pressure is propounded on the basis of the total pressure and the concentration of a specific element in the mixture.

In general, Partial pressure = Total pressure × Concentration