Answer
9.0 moles of $H_{2}$
Work Step by Step
$3H_{2}+N_{2}$ -> $2NH_{3}$
mole of $H_{2}$ =
$\frac{(6molNH_{3})\times(3molH_{2})}{2molNH_{3}}$
=9.0 moles of $H_{2}$
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