Answer
d) 1.14 mol.
Work Step by Step
Mass of NH$_{3}$ = 6.50g
Molar mass of N = 14.0gmol$^{-1}$
Molar mass of H = 1.00gmol$^{-1}$
Since there are 3 moles of Hydrogen in NH$_{3}$:
Molar mass of NH$_{3}$ = (1 * 14.0) + (3 * 1.00) = 17.0gmol$^{-1}$
n = $\frac{m}{M}$
=> n(NH$_{3}$) = $\frac{m(NH_{3})}{M(NH_{3})}$
=> n(NH$_{3}$) = $\frac{6.50g}{17.0gmol^{-1}}$
=> n(NH$_{3}$) = 0.382 mol
Since there are 3 moles of H in every 1 mole of NH$_{3}$:
Number of moles of H in 0.382mol of NH$_{3}$ = 3 * 0.382mol $\approx$ 1.14 mol
Hence, correct answer is d) 1.14 mol
