Enthalpy of neutralization is always a constant when a strong acid is neutralized by a strong base: account for the statement.

Explanation

(i)Enthalpy of neutralization of strong acid by a strong base is always a constant and it is equal to -57.32 kJ irrespective of which acid or base is used.
(ii)Because strong acid or strong base means it is completely ionized in solution state. For e.g. NaOH (strong base) is neutralized by HCl (strong acid), due to their complete ionization, the net reaction take place is only water formation. So the enthalpy of neutralization is always constant for strong acid by a strong base.
`H^(+) Cl^(-) + Na^(+) OH^(-) to Na^(+)Cl^(-) +H_2O`
`H^(+)NO_3^(-) + K^(+)OH^(-) to K^(+)NO_3^(-) + H_2O`
(Net reaction ) `H^(+) + OH^(-) to H_2O " " DeltaH`=-57.32 kJ