Given : `S_((s))+(3)/(2)O_(2(g))rarrSO_(3(g)+2X Kcal`
`SO_(2(s))+(1)/(2)O_(2(g))rarrSO_(3(g)+Y Kcal`
The heat of formation of `SO_(2)` is `:-`

Options

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

Answer

C

Explanation

Given, `S+(3)/(2)O_(2) to SO_(3),DeltaH_(1)=-2xkJ`
`SO_(2)+(1)/(2)O_(2) to SO_(3),DeltaH_(2)=-ykJ`
`S+O_(2)to SO_(2),DeltaH_(3)=-zkJ`
From Hess's law
`DeltaH_(3)+DeltaH_(2)=DeltaH_(1)`
`-z-y=-2x`
`z=2x-y`