Answer:
From the given equation, we can see that for every 2 moles of Al, we get 3 moles of H2
So, we can say the the number of moles of H2 is 3/2 times the number of moles of Al
We are given the number of moles of Al and we have to find the number of moles of H2
We have deduced the relationship:
Moles of Al * 3 / 2 = Moles of H2
Replacing the variables with given values
3.5 * 3 / 2 = Moles of H2
Moles of H2 = 5.25 moles