Answer;
17.25 moles of hydrogen
Explanation;
The equation for the reaction;
2HI (g) → H₂(g) + i₂ (g)
34.5 moles of Hydrogen iodide are decomposed;
The mole ratio of HI to Hydrogen = 2 : 1
Therefore;
moles of hydrogen = (34.5/2) ×1
= 17.25 moles
Therefore; 17.25 moles of hydrogen will be produced when 34.5 moles of Hydrogen iodide are decomposed