The reaction $2 NH_3 + 3 O_2 \rightarrow 2 NO_2^- + 2 H^+ + 2 H_2O$ is carried out by which of the following microorganisms?

Conversion of $NH_{3} \rightarrow NO_{2}^{-} \rightarrow NO_{3}^{-}$ is called:

The conversion of ammonia into nitrites and nitrates is called

Select the correct matches.
$I$ Nitrosomonas - Nitrite to nitrate
$II$ Thiobacillus - Denitrification
$III$ Nostoc - Free-living nitrogen-fixer
$IV$ Azotobacter - Anaerobic nitrogen-fixer

Match Column $- I$ with Column $- II.$

Column $- I$	Column $- II$
$(a)$ Nitrococcus	$(i)$ Denitrification
$(b)$ Rhizobium	$(ii)$ Conversion of ammonia to nitrite
$(c)$ Thiobacillus	$(iii)$ Conversion of nitrite to nitrate
$(d)$ Nitrobacter	$(iv)$ Conversion of atmospheric nitrogen to ammonia

Choose the correct answer from the options given below.

The source of energy for non-biological nitrogen fixation is