Assertion: pH  of  water  increases  with  an  increase  in temperature. Reason: Kw  of  water  increases  with  increase  in temperature.

2 H O H OH H Ve Autoionization of water is endothermic thus using van’t Hoff equation 2 1 1 2 K H 1 1 ln K R T T As temperature increases w K also increases Thus, at higher temperature than  25 C , 14 w K 10 Thus, at higher temperature, 14 H OH 10 Hence, pH decreases.