At 90 degree centigrade ,pure water [H+]=10 to the power -6 mole/litre.The value of Kw at 90 degree centigrade?

can some please tell me how to solve this question.

H₂O ⇄ H⁺ + OH⁻

Water dissociates in this manner. Now ionic product of water is Kw

Kw = [H⁺][OH⁻] mol²dm⁻⁶

Kw is a constant for water in a particular temperature.

With increase in temperature Kw increases and if the temperature is decreased the Kw value decreases.

In higher temperature the equilibrium of the stated equation shifts to the right, so more dissociation occurs leading increase in Kw value, with decrease temperature the equilibrium shifts left and Kw value decreases.

At 90°C the Kw value of water is 38 X 10⁻¹⁴ mol²dm⁻⁶