Which of the following reactions will define `DeltaH_(f)^(@)` ?

Options

A. `C("diamond")+O_(2)(g)toCO_(2)(g)`
B. `(1)/(2)H_(2)(g)+(1)/(2)F_(2)(g)toHF(g)`
C. `N_(2)(g)+3H_(2)(g)to2NH_(3)`
D. `CO(g)+(1)/(2)O_(2)(g)toCO_(2)(g)`

Answer

B

Explanation

Standard enthalpy of formation is equal to enthalpy change for the preparation of `1` mole of a compound from its standard state.
Therefore, for the reaction
`(1)/(2)H_(2)(g)+(1)/(2)H_(2)(g)toHF(g)`
`DeltaH_(f)^(@)=DeltaH^(@)`