`5.0 g` of a sample containing `(NH_(4))_(2) SO_(4)` & inert impurity `(X)` was boiled with excess of `NaOH` and the `NH_(3)(g)` so produced was absorbed in `200ml` of `0.5 M H_(2)SO_(4)` solution in another vessel. The unreacted `H_(2)SO_(4)` required `400ml` of `0.4 M` solution of `NaOH` for exact neutralization.
Calculate weight `%` of nitrogen in given sample

Options

A. `56`
B. `5.6`
C. `11.2`
D. none of these

Answer

C

Explanation

`{:(,H_(2)SO_(4)" "+,2NaOHrarrNa_(2)SO_(4)+H_(2)O),(,,400xx0.4):}`
`80m "mol" = 160 m "mol"`
Remaining `H_(2)SO_(4) = 200xx0.5 - 80 m mol`
`= 100 - 80 = 20 m mol`
`{:(,2NH_(3)" "+,H_(2)SO_(4)rarr(NH)_(4)SO_(4)),(,40 m "mol" ,20 m "mol"):}`
`%N = (40xx10^(-3)xx14)/(5) xx 100 = 11.2`