Answer
$\Delta S = 6.34 J/K $
Work Step by Step
As,
$Q=W=nRT ln(\frac{v_{f}}{v_{i}})$
$\Delta S=\frac{Q}{T} = \frac{W}{T} = nRT ln(\frac{v_{f}}{v_{i}})$
$\frac{v_{f}}{v_{i}} = \frac{0.800}{0.200} = 4.00 $
$\Delta S = (0.55)(8.31)ln(4.00) = 6.34 J/K $
