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delta(f) U^(Ө) "of formation of" CH(4)(g...

`delta_(f) U^(Ө) "of formation of" CH_(4)(g)` at a certain temperature is `-393Jmol^(-1).` The value of `delta H^(Ө)is:`

A

zero

B

` lt Delta_(f)U^(c-)`

C

`gt Delta_(f)U^(c-)`

D

equalto `Delta_(f)U^(c-)`

Text Solution

Verified by Experts

The correct Answer is:
b
`CH_(4)(g) + 2O_(2)(g) rarr CO_(2)(g) + 2H_(2)O(l)`
`Deltan_(g) = ( n_(p)-n_(r))_(g)=1-3= -2`
`Delta_(f)H^(@) =Delta_(f)U^(@) + Deltan_(g) RT`
As `Deltan_(g) = - 2 , Delta_(f)H^(@) lt Delta_(f) U^(@)` .
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