Question

pH of ${10}^{-7}\text{M NaOH}$ is:

• A. 7
• B. 7.3010
• C. 6.6990
• D. none of these

Answer 1

Answer: (B)

Given-that, $[O{H}^{-}]={10}^{-7}+{10}^{-7}$ (from water) $\therefore$ $[O{H}^{-}]=2\times {10}^{-7}$ $\therefore$ $pOH=-\log [O{H}^{-}]$ $=-\log 2\times {10}^7$ $=6.6990$ $\therefore$ $pH=14-6.6990$ $=7.3010$