Question

One mole of a substance is cooled at the rate of $0.4kJ{min}^{-1}$ as shown in the graph. Curve AB, points B and C and curve CD represent respectively, the cooling of the liquid, start of freezing, completion of freezing and cooling of the solid based on this data. The entropy of fusion in $Jmol{K}^{-1}$ is:

• A. 10
• B. 20
• C. 30
• D. 40

Answer 1

The correct option is C 30

The cooling shows fusion process for $30$ minute $(40-10)$ at $400K$.

$\Delta S=\frac{q}{T}=\frac{0.4\times {10}^3\times 30}{400}=30Jmol{K}^{-1}$