Question

what is the fraction of the mass of ammoniya due to netrons

Answer 1

Molar mass of NH₃ = 14 + 3
= 17 g
Number of neutrons in Nitrogen = 7
Number of neutrons in H = 0
In one molecule of Ammonia there are 7 neutrons
17 g of NH₃ = 6.022 $\times$10²³ molecules
Number of neutrons in 17 g = 7$\times$6.022$\times$10²³ neutrons
Mass of one neutron = 1.67$\times$10^-27 kg
Mass of ​7$\times$6.022$\times$10²³ neutrons = ​7$\times$6.022$\times$10²³$\times$1.67$\times$10^-27
= 70.397$\times$10^-4kg = 7.0397g
Fraction of mass = (mass of neutrons in 17 g / mass of NH₃) $\times$ 100
= (7.0397 / 17)$\times$100
= 41.41 %