Question

Consider the following experimental set-up with stop cocks $S_1,S_2,S_3,S_4$ and taps $T_1,T_2,T_3,T_4$.

A pH meter is immersed in the bucket of the original set up shown it shows reading of 7 Now $S_1$ is the first opened and all content is allowed to drain out into the bucket pH of the solution in the bucket is measured again Similarly $S_2,S_{3}and{S}_4$ are sequentially opened and the pH of the solution in the bucket is measured each time after complete drainage Opening which stop cock would cause maximum pH change ( increase/decrease) compared to the previous pH in bucket

• A. $S_1$
• B. $S_2$
• C. $S_3$
• D. $S_4$

Answer 1

Answer: (A), (B), (D)

The correct options are
A $S_1$
B $S_2$
D $S_4$

Opening stop cocks $S_1,S_2$ and $S_4$ would cause maximum pH change ( increase/decrease) compared to the previous pH in bucket. When an acid is added to a neutral solution or a base is added to acid solution, maximum pH change will occur.

When $S_3$ is opened, an acid is added to acidic solution. Hence, pH change is not large.