What is the effect of temperature on ionic porduct of water and why?

Explanation

Ionic product of water is :
`2H_2O hArr H_3O^(+) + OH^-`
Ionic product `K_w=[H_3O^+][OH^-]`
Ionic product increases with increase of temperature because the dissociation of water (endothermic reaction) increases with increase of temperature.
Now , pH =-log `[H_3O^+]`. with increase in concentration of `H_3O^+` ions, the pH of the neutral solution will decrease.