From your balanced equation;

2 H

_{2}S + 3 O

_{2} 2 SO

_{2} + 2 H

_{2}O

for every molecule (and hence mole) of H

_{2}S you put in, given excess oxygen, you form one molecule of SO

_{2}. So, if you have 9.7 mol of H

_{2}S, how many moles of SO

_{2} can you form?