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Heat of atomisation of NH(3) and N(2)H(4...

Heat of atomisation of `NH_(3)` and `N_(2)H_(4)` are `"x kcal mol"^(-1)` and `"y kcal mol"^(-1)` respectively. Calculate average bond energy of `N-N` bond.

A

`(4y - 3x)/(3) kcal mol^(-1)`

B

`(2y - 3x)/(3) kcal mol^(-1)`

C

`(4y - 3x)/(4) kcal mol^(-1)`

D

`(3y - 4x)/(3) kcal mol^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
D
`NH_(3) rarr N + 3H " "H_(at) = x`
`x = B.D "of" 3(N - H) `
`(N - H) = x/3 " "…(i)`
`N_2H_4 rarr 2N + 4N Delta H_(at) = Y`
`1(N - N) + 4(N - H) = y`
`(N - N) + 4(x/3) = y`
`(N - N) = y - 4/3 x`
`(N - N) = (3y - 4x)/(3) kcal//mol`
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