1. Three elements having single electrons in their
outermost shell. Ans. Hydrogen, Lithium, Sodium, Potassium.
2. Three elements with filled outermost shell. Ans. Helium, Neon, Argon, Krypton, Xenon.
3. Three elements having 7 electrons in their outermost
shell. Ans.
Fluorine, Chlorine, Bromine, Iodine.
