The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons respectively in their outermost shells. Write the group numbers in which these elements are placed in the Modern Periodic Table. Write the electronic configuration of the atoms of B and D and the molecular formula of the compound formed when B and D combine.
A - 1st, B - 13th, C - 15th, D - 17th
B = 2, 8, 3
D = 2, 8, 7
Molecular Formula: BD3