For the given heat of reaction,
(i) `C(s)+O_(2)(g)CO_(2)(g)+97Kcal`
(ii) `CO_(2)(g)+C(s)=2CO(g)-39Kcal`
the heat of combustion of `CO(g)` is:

Options

A. `68Kcal`
B. `-68Kcal`
C. `+489Kcal`
D. None

Answer

B

Explanation

Subtracting equattion (ii) from equation (i), we get
`C(s)+O_(2)(g)+97Kcal`
`(CO_(2)(g)+C(s)=2CO(g)-39Kcal)/(or -CO_(2)(g)+O_(2)(g)-2CO(g)+136Kcal)`
or, `2CO(g)+O_(2)=CO_(2)(g)+136Kcal`
or, `CO(g)+1//2O_(2)(g)=CO_(2)(g)68Kcal` ltgbrgt Required value `=68Kcal`