Past paper question (1 Viewer)

[highshill]

https://thsconline.github.io/s/?view=1818&id=0ByEFYhkkDQBKdFVOOFptQ0NGckE&n=James Ruse 2010 w. sol
Out of the past paper the only question I don't get is question 17 (a)
Can someone help.

 

[jazz519]

the volumes of the gases if they are in the same container will also obey the mole ratio rule. So pretty much hydrogen is a limiting reagent, that means all of it will react so 0mL of H2, 40mL of N2 reacts so 10mL remains and 80mL of NH3 remains