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JEE Main levelSingle correct optionDifficulty 2 of 3td138

The enthalpy of fusion of benzene is $9.87 kJ mo l^{- 1}$ and its melting point is $278.5 K$ . The entropy of fusion is closest to

A $35.4 J mo l^{- 1} K^{- 1}$
B $0.0354 J mo l^{- 1} K^{- 1}$
C $2748795 J mo l^{- 1} K^{- 1}$
D $70.9 J mo l^{- 1} K^{- 1}$

Answer: A

At the melting point solid and liquid are in equilibrium, so

Δ_{f u s} S = Δ_{f u s} H / T_{m} = 9870/278.5 = 35.4 J mo l^{- 1} K^{- 1}

. Forgetting to convert kJ to J gives

0.0354

, and multiplying instead of dividing gives a huge number.

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