Verified Solution • 2025–26 Session moderate

QJEEAdv08Chdbe5: JEE Advanced 2008 Chemistry - Class 12 JEEAdv08Chdbe5 Solution: A solution of colourless salt H on boiling with excess NaOH…

A solution of colourless salt H on boiling with excess NaOH produces a non-flammable gas. The gas evolution ceases after sometime. Upon addition of Zn dust to the same solution, the gas evolution restarts. The colourless salt(s) H is(are):

Multiple Choice Options

  • A NH 4_4 NO 3_3
  • B NH 4_4 NO 2_2
  • C NH 4_4 Cl
  • D (NH 4_4 ) 2_2 SO 4_4

Step-by-Step Verified Solution

The colourless salt H is either NH 4_4 NO 3_3 or NH 4_4 NO 2_2 . The colourless salt produces NH 3_3 gas (non-inflammable) on boiling with excess of NaOH. On addition of zinc dust (a reducing agent) to this solution, sodium nitrite or sodium nitrate will liberate NH 3_3 gas again.

NH 4_4 NO 3_3 + NaOH →\to NH 3_3 + NaNO 3_3 + H 2_2 O

7NaOH + NaNO 3_3 + 4Zn →\to 4Na 2_2 ZnO 2_2 + NH 3_3 + 2H 2_2 O

NH 4_4 NO 2_2 + NaOH →\to NaNO 2_2 + NH 3_3 + H 2_2 O

3Zn + 5NaOH + NaNO 2_2 →\to 3Na 2_2 ZnO 2_2 + NH 3_3

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