Question

Assertion: Quick lime reacts with water to form slaked lime.

Reason: It is a slow chemical reaction.

• A. If both assertion and reason are true and the reason is the correct explanation of assertion.
• B. If both assertion and reason are true but the reason is not the correct explanation of assertion.
• C. If the assertion is true but the reason is incorrect.
• D. If the assertion is incorrect but the reason is correct.

Answer 1

The correct option is C

If the assertion is true but the reason is incorrect.

The explanation for the correct option.

(C) If the assertion is true but the reason is incorrect.

The explanation for the assertion.

Quick lime reacts with water to form slaked lime.

Quick lime$\mathbf{\left(}\mathbf{CaO}\mathbf{\right)}$ reacts with water$\mathbf{\left(}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\right)}$ to produce slaked lime$\mathbf{\left(}\mathbf{Ca}{\mathbf{\left(}\mathbf{OH}\mathbf{\right)}}_{\mathbf{2}}\mathbf{\right)}$.

$\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{aq}\right);∆\mathrm{H}=-359{\mathrm{kJmol}}^{-1}$

Hence, the assertion is correct.

The explanation for the reason statement.

It is a slow chemical reaction.

1. The reaction of quick lime with water is exothermic and spontaneous.
2. It is a fast chemical reaction.

Hence, the reason is incorrect.

Since the assertion is true but the reason is incorrect.

Therefore, The correct option is (C).