Q28 / 90 · JEE Main 2021 (25 Jul Shift 2) · Chemistry

$0.8 g$ of an organic compound was analysed by Kjeldahl's method for the estimation of nitrogen. If the percentage of nitrogen in the compound was found to be $42 %$ , then....... $mL$ of $1 M$ $H_{2} {SO}_{4}$ would have been neutralized by the ammonia evolved during the analysis.

Correct answer: 12

Solution

Organic compound : $0.8 gm$

wt. of $N = (\frac{42}{100} \times 0.8) gm$

mole of $N = \frac{42 \times 0.8}{100 \times 14} = \frac{2.4}{100} mol$

moles of ${NH}_{3} = \frac{2.4}{100}$

$Molarity \times Volume (L) = number of moles$

$\frac{1.2}{100} = 1 \times V (L)$

$\Rightarrow V_{H_{2} {SO}_{4}} = \frac{1.2}{100} L = 12 mL$

Hence, the correct answer is 12.