Explain the adsorption of nitrogen on iron.

Explanation

When nitrogen gas is brought in contact with iron at 83 K, it is physisorbed on iron surface as nitrogen molecules, `N_(2)`. As the temperature is increased the amount of nitrogen adsorbed decreases rapidly and at room temperature, practically there is no adsorption of nitrogen on iron. At 773 K and above, nitrogen is chemisorbed on the iron surface as nitrogen atoms.