Ammonia can be produced from the reaction of hydrogen with nitrogen - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2023 - Paper 2

To calculate the percentage by mass of nitrogen in ammonia (NH₃), we need to consider the molar mass of ammonia. The molar mass of nitrogen (N) is 14 g/mol and that of hydrogen (H) is 1 g/mol. Since there are three hydrogen atoms, the total molar mass of NH₃ is:

$M(NH₃) = M(N) + 3 imes M(H) = 14 + 3 imes 1 = 17 ext{ g/mol}$

The percentage by mass of nitrogen is then calculated using the formula:

$ext{Percentage of N} = \left( \frac{M(N)}{M(NH₃)} \right) \times 100 = \left( \frac{14}{17} \right) \times 100 \approx 82.35\%$

Thus, the closest answer is D 82%.