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

C(graphite) `+O_(2)(g)rarrCO_(2)(g)`,
`DeltaH=xkJ mol^(-1)`
C(graphite) `+O_(2)(g)rarrCO_(2)(g)`,
`DeltaH=xkJmol^(-1)`
ii) `C(g)+(1)/(2)O_(2)(g)rarrCO_(2)(g),DeltaH=ykJmol^(-1)`
iii) `CO(g)+(1)/(2)O_(2)(g)rarrCO_(2)(g),DeltaH=zkJmol^(-1)`
Equation (i) can be obtained by adding (ii) and (iii) hence `x=y+z`