MCQ
At $298\, \mathrm{~K}$, the enthalpy of fusion of a solid $(\mathrm{X})$ is $2.8 \,\mathrm{k} \mathrm{J}\, \mathrm{mol}^{-1}$ and the enthalpy of vaporisation of the liquid $(X)$ is $98.2 \,\mathrm{~kJ}\, \mathrm{~mol}^{-1}$. The enthalpy of sublimation of the substance $(\mathrm{X})$ in $\mathrm{kJ} \,\mathrm{mol}^{-1}$ is $.....$ (in nearest integer)
  • A
    $99$
  • B
    $100$
  • $101$
  • D
    $201$

Answer

Correct option: C.
$101$
c
$\Delta \mathrm{H}_{\text {sub }}=\Delta \mathrm{H}_{\text {fus. }}+\Delta \mathrm{H}_{\text {vap. }}$

$=2.8+98.2$

$=101\, \mathrm{KJ} / \mathrm{mol}$

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