Question

On adding $HCl$ to $H_{2}O$, the $pH$ of the system:

• A. increases
• B. decreases
• C. remains constant
• D. can't be predicted

Answer 1

Answer: (B)

decreases

$HCl$ is acidic in nature and $H_{2}O$ is neutral. On mixing the two, the solution becomes acidic in nature. Hence, the $pH$ of the system decreases.

$HCl+H_{2}O\rightleftarrows H_3{O}^{+}+{Cl}^{-}$