Answer : The correct option is, (C) 1.4 g
Solution : Given,
Mass of ammonia = 1.7 g
Molar mass of ammonia = 17 g/mole
Molar mass of nitrogen = 28 g/mole
First we have to calculate the moles of ammonia gas.
![\text{ Moles of }NH_3=\frac{\text{ Mass of }NH_3}{\text{ Molar mass of }NH_3}=\frac{1.7g}{17g/mole}=0.1moles](https://tex.z-dn.net/?f=%5Ctext%7B%20Moles%20of%20%7DNH_3%3D%5Cfrac%7B%5Ctext%7B%20Mass%20of%20%7DNH_3%7D%7B%5Ctext%7B%20Molar%20mass%20of%20%7DNH_3%7D%3D%5Cfrac%7B1.7g%7D%7B17g%2Fmole%7D%3D0.1moles)
The given balanced reaction is,
![N_2(g)+3H_2(g)\rightarrow 2NH_3(g)](https://tex.z-dn.net/?f=N_2%28g%29%2B3H_2%28g%29%5Crightarrow%202NH_3%28g%29)
From the reaction, we conclude that
As, 2 moles of ammonia produced from 1 mole of nitrogen
So, 0.1 moles of ammonia produced from
moles of nitrogen
The moles of nitrogen = 0.05 moles
Now we have to calculate the mass of nitrogen.
![\text{ Mass of nitrogen}=\text{ Moles of nitrogen}\times \text{ Molar mass of nitrogen}](https://tex.z-dn.net/?f=%5Ctext%7B%20Mass%20of%20nitrogen%7D%3D%5Ctext%7B%20Moles%20of%20nitrogen%7D%5Ctimes%20%5Ctext%7B%20Molar%20mass%20of%20nitrogen%7D)
![\text{ Mass of nitrogen}=(0.05moles)\times (28g/mole)=1.4g](https://tex.z-dn.net/?f=%5Ctext%7B%20Mass%20of%20nitrogen%7D%3D%280.05moles%29%5Ctimes%20%2828g%2Fmole%29%3D1.4g)
Therefore, the mass of nitrogen must be react is, 1.4 g.