Question

Which does not happen when water is added to quick lime?

• A. The hissing noise is produced
• B. A precipitate is formed
• C. There is a change in temperature
• D. There is a change in the color of the product

Answer 1

The correct option is D

There is a change in the color of the product

The explanation for the correct option:

(D) There is a change in the color of the product

1. The formula for quick lime is CaO and when it reacts with water(H₂O) it forms calcium hydroxide[Slaked lime-Ca(OH)₂].
2. No change in color is observed.

Reaction involved:

$\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to \mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)+\mathrm{Heat}$

The explanation for the incorrect options:

(A) The hissing noise is produced

There is a hissing sound produced during the reaction.

(B) A precipitate is formed

Slaked lime formed is a precipitate.

(C) There is a change in temperature.

The reaction is exothermic as heat is released.

Hence, the correct option is (A).