Question

Which of the following is the correct description of calcium oxide?

• A. Very stable
• B. Prepared by the process of calcination
• C. Low affinity for water
• D. Less efficient desiccant than silica gel

Answer 1

The correct option is B Prepared by the process of calcination

Option $\left(B\right)$ is correct.

A) Calcium oxide (or quicklime) is not stable and, when cooled, will spontaneously react with $C{O}_2$ from the air until, after enough time, it will be completely converted back to calcium carbonate unless slaked with water to set as lime plaster or lime mortar.

B) $CaO$ is prepared by the process of calcination.It involves thermal decomposition of calcium carbonate in a lime kiln.

$CaC{O}_3\left(s\right)\to CaO\left(s\right)+C{O}_2\left(g\right)$

C) $CaO$ has a high affinity for water.It reacts with water to form calcium hydroxide.It is a reversible reaction.As it hydrates, an exothermic reaction results and the solid puffs up. The hydrate can be reconverted to quicklime by removing the water by heating it to redness to reverse the hydration reaction.

D) Calcium oxide is more efficient desiccant than silica gel.