The heat of atomisation of PH(3) is 228 ...

The heat of atomisation of `PH_(3)` is 228 K cal/mol and that os `P_(2)H_(4)` is `335` kCal/mol. The energy of `P-P` is (in kcal)

A

102k cal `mol^(-1)`

B

51 k cal `mol^(-1)`

C

26k cal `mol^(-1)`

D

204 k cal `mol^(-1)`

Verified by Experts

The correct Answer is:

B

Bond dissociation energy of `PH_(3)(g)= 228k cal mol^(-1)`
`P-H` bond energy `=(228)/(3)= 76k cal mol^(-1)`

Bond energy of `4(P-H)+(P-P) = 355 k cal mol^(-1)` or `4 xx 76 + (P-P)= 355` kcal `mol^(-1) rArr 51k cal mol^(-1)`

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