Question

100mL of solution of $pH=6$ is diluted to 1 litre. Resulting solution has $pH$ is:

• A. 7
• B. 6.8
• C. 7.3
• D. 6.4

Answer 1

The correct option is A 7

A solution with pH 6 has concentration ${10}^{-}$${}^6$ M

If it is diluted to 1 litre i.e in 1000 times, it becomes ${10}^{-}$${}^6$ / 1000

= ${10}^{-}$${}^9$ M

Water has pH = 7. So [$H_3{O}^{+}$] = ${10}^{-}$${}^7$ M

[$H_3{O}^{+}$] in dilute acidic solution will approach ${10}^{-}$${}^7$ M. The concentration cannot be less than ${10}^{-}$${}^7$ M.

So the pH of the resulting solution will be approx 6.96 i.e 7.

So A is the correct option.