Ncert Exercises & Solutions

Reactions carried out by N₂ fixing microbes include

(i) $2 {NH}_{3}$ $+$ $3 O_{2}$ $\to$ $2 {NO}_{2}^{-}$ $+$ $2 H^{+}$ $+$ $2 H_{2} O$

(ii) $2 {NO}_{2}$ $+$ $O_{2}$ $\to$ $2 {NO}_{3}$

Which of the following statements about these equations is not true?

1.	Step (i) is carried out by Nitrosomonas or Nitrococcus
2.	Step (ii) is carried out by Nitrobacter
3.	Both steps (i) and (ii) can be called nitrification
4.	Bacteria carrying out these steps are usually photoautotrophs