Question

How many $O$ atoms are in $Zn{(Cl{O_3})_2}$?

Answer 1

Hint: As we already know that the number of atoms of any element inside the bracket is multiplied by the number written outside the bracket and thus it tells us about the actual number of atoms of an element present in the given compound.

Complete step by step answer:
As we have learnt that the number of atoms of an element which are present inside the bracket in a compound can be calculated by simply multiplying them with the number present outside the bracket enclosing it.
Thus, in the given compound zinc chlorate, $Zn{(Cl{O_3})_2}$, the number outside the bracket which is $2$ should be multiplied with the number of atoms of oxygen present inside the brackets so as to obtain a total number of oxygen atoms. As we can see that there are three atoms of oxygen inside the bracket, so we will simply multiply these three atoms with $2$ and hence we will get:
$O = 3 \times 2 = 6$
Therefore, we can say that the total number of oxygen atoms in zinc chlorate are $6$.
Similarly, if we are asked to find the number of chlorine atoms, we can calculate it by again multiplying the number of chlorine atoms inside the bracket by $2$. We see that there is only one chlorine atom inside the bracket, so we will get:
$Cl = 1 \times 2 = 2$

Thus, we can say that there are $2$ chlorine atoms and $6$ oxygen atoms along with a single zinc atom in zinc chlorate.

Note: Always remember that the number written outside the brackets in a compound are always multiplied by the individual number of atoms of each element which is present inside the bracket. Also, zinc chlorate is generally used as an oxidising agent in explosives.