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

Identify $X$ and $Y$ in the given nitrogen cycle chart.

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

The amount of nitrogen fixed electrochemically and photochemically is:

Which organisms actively participate in the nitrogen cycle in nature?

Nitrates of soil are also leached deep into the Earth by . . . . . . .