The question is incomplete. Complete question is provided below:
Which energy profile best shows that the enthalpy of formation of CS2 is 89.4 kj/mol?
A. C(s) + 2S(s) → CS2(l) + 89.4 kJ.B. C(s) + 2S(s) + 89.4 kJ → CS2(l).C. C(s) + 2S(s) + 89.4 kJ → CS2(l) + 89.4 kJ.D. C(s) + 2S(s) → CS2(l)........................................................................................................................
Correct Answer: Option B i.e. C(s) + 2S(s) + 89.4 kJ → CS2(l)
Reason:
For th formation of CS2 from C and S, heat has to be supplied to the system. In the case, where heat has to be supplied, it is written in left hand side of reaction i.e. on reactant side. Hence correct representation for enthalpy of formation of CS2 is option B.