Which of the following best describes pure, neutral water when the temperature is raised from 25∘C to 40∘C?
a) Its pH becomes greater than 7 because the value of Kw decreases with temperature.
b) Its pH becomes less than 7 because the value of Kw increases with temperature.
c) Its pH remains exactly 7 because the pH of neutral water is temperature-independent.
d) Its pH becomes greater than 7 because the value of Kw increases with temperature.