MCQ
For the following Assertion and Reason, the correct option is

Assertion : The $pH$ of water increases with increase in temperature.

Reason : The dissociation of water into $H^+$ and $OH^-$ is an exothermic reaction.

  • A
    Both assertion and reason are true, but the reason is not the correct explanation for the assertion.
  • Both assertion and reason are false.
  • C
    Assertion is not true, but reason is true.
  • D
    Both assertion and reason are true, and the reason is the correct explanation for the assertion.

Answer

Correct option: B.
Both assertion and reason are false.
b
$\mathrm{H}_{2} \mathrm{O}(\ell) \rightleftharpoons \mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{OH}_{(\mathrm{aq})}^{-}$

For ionization of $\mathrm{H}_{2} \mathrm{O}: \Delta \mathrm{H}>\mathrm{O}$ $\Rightarrow$ Endothermic

On temperature increase reaction shifts forward

$\Rightarrow$ both $\left[\mathrm{H}^{+}\right]$ and $\left[\mathrm{OH}^{-}\right]$ increase

$\Rightarrow \mathrm{pH} \;and\; \mathrm{pOH}$ decreases.

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