The absolute enthalpy of neutralisation of the reaction
`MgO(s) + 2HCl(aq) to MgCl_(2)(aq) + H_(2)O(l)` will be

Options

A. less than -57.33 KJ `"mol"^(-1)`
B. `-57.33 KJ "mol"^(-1)`
C. greater than `-57.33 KJ "mol"^(-1)`
D. 57.33 KJ `"mol"^(-1)`

Answer

A

Explanation

Heat of neutralisation of strong acid and strong base is -57.33 KJ. MgO is weak base while HCl is strong acid. So the heat of neutralisation of MgO and HCl is lower than `-57.33 KJ ` because MgO requires some heat for ionisation , therefore the net released amount of heat is decreased.