The correct answer is six.
In the reaction, one molecule of bromine (Br2) combines with two molecules of potassium chloride (KCl) to form two molecules of potassium bromide (KBr) and one molecule of chlorine gas (Cl2).
Each molecule of potassium bromide (KBr) contains one potassium atom (K) and one bromine atom (Br), so the two molecules of potassium bromide contain a total of two potassium atoms and two bromine atoms.
The molecule of chlorine gas (Cl2) contains two chlorine atoms (Cl).
Therefore, the products of the reaction contain a total of two potassium atoms, two bromine atoms, and two chlorine atoms, which gives a total of six atoms.