Question

How many moles of H2 and N2 can be formed by the decomposition of 0.250 mol of ammonia, NH3?

Is it 0.250*3mol H2=0.75

0.25*1mol N2=0.25

Am I correct?

Answer 1

I think your error is caused by not balancing the equation. ALWAYS start with a balanced equation.
2NH3 ==> N2 + 3H2
0.250mols NH3 x (1 mol N2/2 mol NH3) = 0.250 x 1/2 = ? mols N2

0.250 mols NH3 x (3 mols H2/2 mols NH3) = 0.250 x 3/2 = ? mols H2