Step 1
The reaction must be written and balanced:
5C(s) + 2SO2(g) → CS2(g) + 4CO(g)
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Step 2
Procedure according to the reaction shown above:
5 x 1 mole C ------- 2 x 1 mole SO2
X ------- 1.42 moles SO2
X = 1.42 moles SO2 x 5 x 1 mole C/2 x 1 mole SO2 = 3.55 moles of C
Answer: 3.55 moles of C