Question

Lime has been left exposed to the atmosphere.

Answer 1

the lime can be react by abosrbing carbon dioocide in atmosphere to become calcium
carbonate

Answer 2

Answer: It will form a milky solution due to the formation of calcium carbonate.

Explanation:

Lime water is a common name for a solution of calcium hydroxide $(Ca(OH)_2)$

When it is exposed to the atmosphere (which is full of carbon dioxide gas), calcium hydroxide will react with carbon dioxide present in atmosphere and form a milky solution due to the formation of calcium carbonate.

The equation for the following reaction is given as:

$Ca(OH)_2(aq.)+CO_2(g)\rightarrow CaCO_3(s)+H_2O$

Hence, the solution of lime water turns milky.