Liquid Sodium Can Be Used as a Heat Transfer Fluid $\times$

Liquid sodium can be used as a heat transfer fluid.Its vapor pressure is 40.0 torr at 633°C and 400.0 torr at 823°C.Calculate its heat of vaporization.

A) 43.4 kJ/mol
B) 52.5 kJ/mol
C) 70.6 kJ/mol
D) 1.00 $\times$ 10² kJ/mol
E) None of these choices is correct.