Question

$pH$ of water is $7.0$ at ${25}^{o}C$. If water is heated to ${70}^{o}C$, the

• A. $pH$ will decrease and the solution becomes acidic
• B. $pH$ will increase
• C. $pH$ will remain constant as $7$
• D. $pH$ will decrease but solution will be neutral

Answer 1

The correct option is D $pH$ will decrease but solution will be neutral

On heating water, $K_w$ increases and thus, $pH$ scale for neutrality changes from $7$ to some lower value.