B belongs to III A group of the periodic table so its valency is 3 (accept 3 e-‘s from other atoms to form stable configuration ) H belongs to I A group of the periodic table so its valance is 1 B H Valency 3 1 To form a compound cross multiply their valencies with the atoms we get the formula So the compound formed is B1H3 Ie., BH3 P belongs to V A group of the periodic table so its valency is 5 .But its configuration is [Ne] 3s2 3p3 Since the p orbital is half filled , it is interested to accept 3 e-‘s into the 3p orbitals from other atoms leaving 1 lone pair(2 electrons) upon it. Mg belongs to IIA ----> valence is 2 Mg P Valency 2 3 To form a compound cross multiply their valencies with the atoms we get the formula So the compound formed is Mg3P2 Solution B belongs to III A group of the periodic table so its valency is 3 (accept 3 e-‘s from other atoms to form stable configuration ) H belongs to I A group of the periodic table so its valance is 1 B H Valency 3 1 To form a compound cross multiply their valencies with the atoms we get the formula So the compound formed is B1H3 Ie., BH3 P belongs to V A group of the periodic table so its valency is 5 .But its configuration is [Ne] 3s2 3p3 Since the p orbital is half filled , it is interested to accept 3 e-‘s into the 3p orbitals from other atoms leaving 1 lone pair(2 electrons) upon it. Mg belongs to IIA ----> valence is 2 Mg P Valency 2 3 To form a compound cross multiply their valencies with the atoms we get the formula So the compound formed is Mg3P2.