JEE Main 2014 · 6 Apr · Shift 1 · Chemistry Q34

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ChemistrySingle correct+4 / -1Question 34 of 90

For the estimation of nitrogen, 1.4 g of an organic compound was digested by Kjeldahl method and the evolved ammonia was absorbed in 60 mL of $\dfrac{M}{10}$ sulphuric acid. The unreacted acid required 20 mL of $\dfrac{M}{10}$ sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is :

10%

Answer and worked solution

Official answer: B

Acid taken: $60\times\frac1{10}\times2=12$ mmol $\ce{H+}$ .
Left over: $20\times\frac1{10}=2$ mmol (titrated by NaOH).
So $\ce{NH3}$ = 10 mmol, i.e. 0.14 g of N.

$\%\text{N}=\frac{0.14}{1.4}\times100=10\%.$

Topics:Qualitative and quantitative analysis of organic compounds Stoichiometry

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JEE Main 2014 · 6 Apr · Shift 1, Chemistry question 34