Question

Which of the following represents the chemical formula of calcium carbonate?

• A. $Ca{CO}_3$
• B. ${Ca}_2{CO}_3$​
• C. $Ca({CO}_3{)}_2$
• D. ${Ca}_{3}C{O}_2$​

Answer 1

The correct option is A $Ca{CO}_3$

Calcium carbonate consist of calcium ion and carbonate ion, i.e., $C{a}^{2+}$and ${{\mathrm{CO}}_3}^{2-}$, which have a charge of +2 and -2 respectively.
$$\begin{array}{ccc}\text{Symbol}& \text{Ca}& {\text{CO}}_3\\ \text{Charge}& \text{+2}& \text{-2}\end{array}$$

On cross-multiplication and balancing the charge, we get the formula as $Ca{CO}_3$.