Answer
1.25 moles C are needed to react with 0.500 mole $SO_2$.
Work Step by Step
1. Find the mole-mole conversion factors:
According to the coefficients: 2 moles $SO_2$ = 5 moles $C$
$\frac{ 2 \space moles \space SO_2}{ 5 \space moles \space C}$ and $\frac{ 5 \space moles \space C}{ 2 \space moles \space SO_2}$
2. Use the mole-mole conversion factors to calculate the amount of equivalent $C$ in moles:
$ 0.500$ mole $SO_2 \times \frac{ 5 \space moles \space C}{ 2 \space moles \space SO_2} = 1.25$ moles C
