Answer
0.29 mol KCN
Work Step by Step
$4Au+8KCN+O_{2}+2H_{2}O$ -> $4KAu(CN)_{2}+4KOH$
mol KCN = $\frac{(29.0gAu)\times(1molAu)\times(8molKCN)}{(197gAu)\times(4molAu)}$
$\approx$ 0.2944162437
=0.29 mol KCN
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