The most active nitrogen-fixing blue-green alga in rice fields is:

Which of the following does not help in ${N_2}$ fixation?

Which element plays an important role in nitrogen fixation?

$N_2 + 8e^- + X + 16 ATP \rightleftharpoons 2NH_3 + Y + 16 ADP + 16 Pi$

$A -$ The enzyme nitrogenase is highly sensitive to molecular oxygen.
$R -$ To protect nitrogenase enzymes,the nodule contains an oxygen scavenger called leghaemoglobin.

Which mineral element plays an essential role in nitrogen fixation?