Reduction of in an alkaline medium gives

Options

A. `H_(2)`
B. `NO_(2)`
C. `NH_(3)`
D. `NO`

Answer

3

Explanation

Reduction of nitrates in acid solution gives either`NO_(2)`or `NO`,or but in alkaline solutions with metals such as zinc or Devarda's alloy `(Cu//Al//Zn)` ammonia is produced:
`3Cu+8HNO_(3)overset("cold dilute")underset(lt 1M)(rarr)2NO+Cu(NO_(3))_(2)+4H_(2)O`
`Cu+3HNO_(3)overset("stronger")underset("acid")(rarr)NO_(2)+Cu(NO_(3))_(2)+H_(2)O`
Devarda's alloy `(Cu//Al//Zn)+NaOHrarrH`
`NO_(3)^(-)+9HrarrNH_(3)+3H_(2)O`
`NO_(2)^(-)+7HrarrNH_(3)+2H_(2)O`
`{:(,NO_(3)^(-),NO_(2),NO,NH_(3)),("Oxidation state of N",(+V),(+IV),(+II),(-III)):}`