Q8 / 155 · WBJEE 2017 · Chemistry

Dissolving NaCN in de-ionised water will result in a solution having

  • A
    $\mathrm{pH} < 7$
  • B
    $\mathrm{pH}=7$
  • C
    $\mathrm{pOH}=7$
  • Correct answer
    D
    $\mathrm{pH}>7$

Solution

$\because$ On dissolving NaCN in de-ionised water, following reaction takes place. $\mathrm{CN}^{-}+\mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{HCN}+\mathrm{OH}^{-}$ CN- ions come from the salt of strong base and weak acid. $\therefore$ The solution becomes basic and $\mathrm{pH}>7$

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

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