Q32 / 180 · COMEDK 2018 · Chemistry

The $\mathrm{pH}$ of $10^{-8} \mathrm{M} \mathrm{HCl}$ solution is

  • A
    8
  • B
    more than 8
  • Correct answer
    C
    between 6 and 7
  • D
    slightly more than 7

Solution

$\mathrm{pH}=-\log \left[\mathrm{H}^{+}\right]$ $$ \begin{aligned} {\left[\mathrm{H}^{+}\right] } &=10^{-8}+10^{-7}=1.1 \times 10^{-7} \\ \mathrm{pH} &=-\log \left(1.1 \times 10^{-7}\right) \\ \mathrm{pH} &=7-\log (1.1) \end{aligned} $$ $\therefore$ It is between 6 and 7 .

Hence, the correct answer is option: 'C'.

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