In the reaction
`S + 3/2 O_2 to SO_3 2x kJ and SO_2 + 1/2 O_2 to SO_3 ykJ`
heat of formationof `SO_2` is

Options

A. `x-y`
B. `2x+y`
C. `x+y`
D. `2x-y`

Explanation

`S+3/2O_(2)toSO_(3)+2x kJ " " …(i)`
`SO_(2)+1/2 O_(2) to SO_(3) + y kJ " " ….(ii) `
`S+O_(2) to SO_(2) + q kJ " " ….(iii)`
Equation (iii) can be obtained by subtracting equation (ii) from (i)
`rArr q = 2x - y kJ `
Enthalpy of formation `(DeltaH_(f)) = - q = - (2x-y) = y - 2x`