BotanyNitrate formation by the following reaction is accomplished by2NO2−+O2⟶2NO3−

Nitrate formation by the following reaction is accomplished by
$2 {NO}_{2}^{-} + O_{2} ⟶ 2 {NO}_{3}^{-}$

A
Nitrococcus
B
Nitrosomonas
C
Nitrobacter
D
Thiobacillus or Pseudomonas

Solution:

The nitrite is oxidised to nitrate with the help of the bacterium Nitrobacter. These steps are called nitrification. These nitrifying bacteria are chemoautotrophs.