Find out the valency of the atoms represented by the Fig. $(a)$ and $(b)$.

(N/A) In Fig. $(a)$,the atom has $2$ electrons in the first shell,$8$ in the second,and $8$ in the third shell. Since the outermost shell is completely filled (octet rule),the valency is $0$.
In Fig. $(b)$,the atom has $2$ electrons in the first shell and $7$ in the second shell. To complete its octet,it needs $1$ electron,therefore its valency is $1$.