Given two processes:
`(1)/(2)P_(4)(s) +3CI_(2)(g) rarr 2PCI_(3)(l), DeltaH =- 635 kJ`
`PCI_(3) (l) +CI_(2)(g) rarrPCI_(5)(s), DeltaH =- 137 kJ` ltbrlt The value of Delta_(f)H^(Theta)` of `PCI_(5)` is

Options

A. `454.5 kJ mol^(-1)`
B. `-454.5 kJ mol^(-1)`
C. `-772 kJ mol^(-1)`
D. `-498 kJ mol^(-1)`

Explanation

`(1)/(4)P_(4)(s)+(3)/(2)CI_(2)(g)rarr PCI_(5)(l),DeltaH^(Theta) =- (635)/(2)kJ`
`PCI_(3)(l)+CI_(2)(g)rarr PCI_(5)(s),DeltaH^(Theta) =- 137kJ`
`ulbar({:(,"On adding,",,),(,"(1)/(4)P_(4)(s)+(5)/(2)C1_(2)(g)rarrPC1_(5)(s),DeltaH^(Theta)=-454.5kJ,,):})`