Question

What is the oxidation state of calcium in calcium carbonate$\left({\mathrm{CaCO}}_3\right)$?

• A. +6
• B. +5
• C. +4
• D. +1
• E. +2

Answer 1

The correct option is E

+2

Explanation:

Oxidation number: Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element.

Calculating the oxidation number of Calcium(Ca) in Calcium carbonate $\left({\mathrm{CaCO}}_3\right)$:

The oxidation state of Carbon(C) = +4

The oxidation state of Oxygen(O) = -2

Consider the oxidation state of Calcium(Ca) = x

Now,

$$\begin{gathered} x+1\times \left(+4\right)+3\times \left(-2\right)=0 \\ x+4-6=0 \\ x=+2 \end{gathered}$$

So, the oxidation number of Calcium in Calcium carbonate is $+2$.

Hence, option (E) is correct.