In which of the following reaction does the heat change represent the heat of formation of water ?

Options

A. `2H_(2)(g)+O_(2)(g)rarr2H_(2)O(l),DeltaH=-116 kcal`
B. `H_(2)(g)+(1)/(2)O_(2)(g)rarrH_(2)O(l),DeltaH=-58 kcal`
C. `H^(+)(aq.)+OH^(-)(aq.)rarr2H_(2)O(l), DeltaH=-13.7 kcal`
D. `C_(2)H_(2)(g)+2(1)/(2)O_(2)(g)rarr2CO_(2)(g)+H_(2)O(l), DeltaH=-310 kcal`

Answer

B

Explanation

Heat of formation is the formation of one mole of the substance from its elements.