1. The period with electrons in the shells K, L, and M.
Ans. Third Period.
2. The group with valency zero.
Ans. Group 18 or Zero group.
3. The family of nonmetals having valency one.
Ans. Halogens.
4. The family of metals having valency one.
Ans. Alkali metals.
5. The family of metals having valency two.
Ans. Alkaline earth metals.
6. The metalloids in the second and third periods.
Ans. Boron and Silicon.
7. Nonmetals in the third period.
Ans. Phosphorus (P), Sulphur (S), Chlorine (Cl) and Argon (Ar)
8. Two elements having valency 4.
Ans. Carbon and silicon.
