Question

Given that
`C(s)+O_(2)(g)rarrCO_(2)(g), DeltaH=-394 kJ`
`2H_(2)(g)+O_(2)(g)rarr2H_(2)O(l), DeltaH=-568kJ`
`CH_(4)(g)+2O_(2)(g)rarrCO_(2)(g)+2H_(2)O(l)DeltaH=-892 kJ`
Heat of formation of `CH_(4)` is
A. `-70` kJ
B. 71.8 kJ
C. `-244` kJ
D. `+782` kJ

Answer 1

Correct Answer - A
`C+O_(2)rarrCO_(2),DeltaH=-394 kJ " ...(i)"`
`2H_(2)+O_(2)rarr2H_(2)O, DeltaH=-568 kJ " ...(ii)"`
`CH_(4)+2O_(2)rarrCO_(2)+2H_(2)O, DeltaH=-892 kJ " ....(iii)"`
(i) + (ii) - (iii) and find the required result.