1.Nitrogenase is the crucial enzyme found in root nodules for N₂ fixation it converts the free nitrogen in the air to Ammonia or other nitrogenous compounds.

2.Yes,it requires a special pink coloured pigment for its functioning called Leg Haemoglobin, present in the root nodules of a legume.It is also considered as oxygen molecule scavenger because it combines with the oxygen molecule and helps in it’s removal. Thus helping enzyme nitrogenase in nitrogen fixation, which only works in absence of molecular oxygen.