Atomic numbers of a few elements are given below: $10, 20, 7, 14$.
$(a)$ What would be the electronic configuration for each of these elements?
$(b)$ Determine the valency of these elements.

(N/A) Electronic configuration:
- For atomic number $10$ (Neon): $(2, 8)$
- For atomic number $20$ (Calcium): $(2, 8, 8, 2)$
- For atomic number $7$ (Nitrogen): $(2, 5)$
- For atomic number $14$ (Silicon): $(2, 8, 4)$
$(b)$ Valency:
- For $10$ (Neon): Valence electrons = $8$,so valency = $8 - 8 = 0$ (Inert gas).
- For $20$ (Calcium): Valence electrons = $2$,so valency = $2$.
- For $7$ (Nitrogen): Valence electrons = $5$,so valency = $8 - 5 = 3$.
- For $14$ (Silicon): Valence electrons = $4$,so valency = $4$.