Question

Analyse the reaction given below:

${\text{CaCO}}_3\text{(aq)}$ + ${\text{H}}_2\text{O}\text{(aq)}$ + ${\text{CO}}_2\text{(g)}$ $\to$ ${\text{Ca(HCO}}_3{)}_2\text{(aq)}$

If X is the total number of oxygen atoms and Y is the total number of carbon atoms present in the chemical reaction after balancing, then determine X + Y.

• A. 9
• B. 12
• C. 16
• D. 8

Answer 1

The correct option is D 8

If we count the number of atoms for the given chemical reaction then we have:

Reactants Products

Elements	No. of atoms	Elements	No. of atoms
Ca	1	Ca	1
C	2	C	2
H	2	H	2
O	6	O	6

The total number of electrons are already balanced on both sides of the chemical equation. Hence, the given chemical equation is already balanced. The value of X is 6 and Y is 2. Therefore, the value of X + Y is 8.