Reaction carried out by $N_2$ fixing microbes include
$2N{H}_3+3O_2\to 2N{O}_2^{-}+2H^{+}+2H_{2}O$ (i)
$2N{O}_2^{-}+O_2\to 2N{O}_3^{-}$ (ii)
Which of the following statements about these equations is not true?

The correct option is C Bacteria carrying out these steps are usually photoautotrophs.

Phototrophic bacteria are a group of bacteria, whose energy for growth is derived from sunlight and their source of carbon comes from carbon dioxide or organic carbon.

So, the correct option is 'Bacteria carrying out these steps are usually photoautotrophs'.