On the basic of thermochemical equations (I),(II)and (III), Find out which of the algebraic relationships given in options (a)to (d) is correct ?
(I)`C("graphite")+O_(2)(g)to CO_(2)(g),`
`Delta_(r)H=XKJmol^(-1)`
(II)`C("graphite")+(1)/(2)O_(2)(g)toCO(g),`
`Delta_(r)H=yKJ mol^(-1)`
`(III) CO(g)+(1)/(2)O_(2)(g)toCO_(2)(g), Delta_(r)H=zKJ mol^(-1)`

Options

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

Answer

C

Explanation

The algebraic relationships of the given reaction is equation (a) `-` equation (b) `=` equation (c)
(a) C (graphite) `+ O_(2) (g) rarr CO_(2) (g) , Delta_(f) H = xkJ mol^(-1)`
(b) `(C ("graphite") + (1)/(2) O_(2) (g) rarr CO (g) , Delta_(f) H = y k J mol^(-1))/(CO (g) + (1)/(2) O_(2) (g) rarr CO_(2) (g) , Delta_(f) H = z kJ mol^(-1))`
Hence, `x - y = z` or `x = y + z`