Question

Write the names and symbols of the constituent elements and identify their valencies from their molecular formulae given below:

KCl, HBr, MgBr₂  K₂O, NaH, CaCl₂ , CCl₄ , HI, H₂S, Na₂S, FeS, BaCl₂.

Answer 1

Molecular formula	Constituent element/Name symbol	Valency
1. KCl	Potassium (K) Chlorine (Cl)	1 1
2. HBr	Hydrogen (H) Bromine (Br)	1 1
3. MgBr2	Magnesium (Mg) Bromine (Br)	2 1
4. K2O	Potassium (K) Oxygen (O)	1 2
5. NaH	Sodium (Na) Hydrogen (H)	1 1
6. CaCl2	Calcium (Ca)  Chlorine (Cl)	2 1
7. CCl4	Carbon (C) Chlorine (Cl)	4 1
8. HI	Hydrogen (H) Iodine (I)	1 1
9. H2S	Hydrogen (H) Sulphur (S)	1 2
10. Na2S	Sodium (Na) Sulphur (S)	1 2
11. FeS	Iron (Fe) Sulphur (S)	2 2
12. BaCl2	Barium (Ba) Chlorine (Cl)	2 1