A substance A has a normal melting point of 250K and normal boiling point of 300 K. Using this information and other information given below $\mathrm{\Delta }{S}_{\text{sublimation }}\text{ at }250\mathrm{K}\text{ [in cal/K-mole] }$

$\text{ [Given : }R=2\mathrm{cal}/\mathrm{K}-\mathrm{mole}]$

Information-1: Entropy of vapourisation at 300 K is $21\mathrm{cal}/\mathrm{K}-\mathrm{mole}$

 Information-2: Latent heat of fusion at 250 K is $2.5\mathrm{kcal}/\mathrm{mole}$

 Information-3: $C_p$ is liquid A and gaseous A is 20  $\mathrm{cal}/\mathrm{K}\text{ mole }$ and $10\mathrm{cal}/\mathrm{K}-\mathrm{mole}$

 Information-4: In $\frac{6}{3}=0.18$