Answer
$\Delta S=4.46\frac{J}{K}$
Work Step by Step
We know that:
$\Delta S=nR\ln(\frac{V_f}{V_i})+nC_V\ln(\frac{T_f}{T_i})$
As volume is constant,
$V_f=V_i=V$
Hence:
$nR\ln(\frac{V}{V})=nR\ln(1)=nR(0)=0$
$\implies \Delta S=0+nC_V\ln(\frac{T_f}{T_i})$
We plug in the known values to obtain:
$\Delta S=3.20(\frac{3}{2}\times 8.314)\ln(\frac{425}{380})=4.46\frac{J}{K}$
