With increase in the temperature of pure (distilled) water, its

ANS:B - pOH and pH both 4ecreases.

As the temperature of pure water increases, the autoionization of water increases as well, leading to changes in both pH and pOH. At 25°C, the pH of pure water is 7, and the pOH is also 7. However, as the temperature increases, the dissociation of water molecules into 𝐻+H+ and 𝑂𝐻−OH− ions increases. Since pH and pOH are the negative logarithms of the hydrogen ion concentration (𝐻+H+) and the hydroxide ion concentration (𝑂𝐻−OH−), respectively, their values change accordingly. Here's what happens:

1. pH decreases and pOH increases:
   • The increase in temperature leads to an increase in the concentration of 𝐻+H+ ions, which lowers the pH (as pH is the negative logarithm of 𝐻+H+). Simultaneously, the concentration of 𝑂𝐻−OH− ions decreases, increasing the pOH (as pOH is the negative logarithm of 𝑂𝐻−OH−).