Give that `C_(s) +O_(2_(g))to CO_(2_((g))), Delta H^(0)=-xkJ`
`2CO_((g))+O_(2_((g)))to 2CO_(2_((g))), Delta H^(0)=-ykJ`.

Options

A. `(y-2x)/(3)`
B. `(y-2x)/(2)`
C. `(2x-y)/(2)`
D. `(x-y)/(2)`

Answer

B

Explanation

`C_((s))+O_(2(g))to CO_(2(g)), Delta H =- xkJJ` ……………(1)
`2CO_((g))+O_(2(g))to 2CO_((g)), Delta H^(Theta)=-ykJ`. ………….(2)
Multiply equation (2) with `(1)/(2)` ,we get
`CO_((g))+(1)/(2) O_(2(g))to CO_(2(g))Delta H^(Theta) = y//2kJ`................(3)
Subtracting equation (3) from equation (1) , we get
`C_((s)) +O_(2(g))to CO_(2(g)), Delta H^(Theta)=-xkJ`
`CO_((g))+(1)/(2) O_(2(g)) to Co _(2(g)), Delta H^(Theta) =-y//2 kJ`
`C_((s))+(1)/(2) _(2(g))to CO_(2(g))`
`Delta H(CO)=-X-(-y//2)`
`=-x+y//2=(y-2x)/(2)`.