Consider the following reaction between zinc and oxygen and choose the correct options out of the options given below
`2Zn(s)+ O_(2)(g) to 2 ZnO_(s): DeltaH=-693.8 kJ mol^(-1)`

Options

A. The enthalpy of two moles of ZnO is less than the total enthalpy of two moles of Zn and one mole of oxygen by 693.8 kJ.
B. The enthalpy of two moles of ZnO is more than the total enthalpy of two moles of Zn and one mole of oxygen by 693.8 kJ.
C. `6938 kJ "mol"^(-1)` energy is evolved in the reaction
D. `693.8 kJ "mol"^(-1)` energy is absorbed in the reaction.

Answer

A, C

Explanation

`DeltaH = H_(p)- H_(r)`. A negative value of `DeltaH` shows that `H_(r) gt H_(p)` or `H_(p) lt H_(r)` i.e. Enthalpy of 2 moles of ZnO is less than enthalpy of 2 mol of zinc and one mol of oxygen by 693.8 kJ.Since `H_(r) gt H_(p)`, 693.8 kJ of energy is evolved in the reaction.