Answer:
The answer to your question is below
Explanation:
a) I will choose three elements of each group
Group IIA Group VIIA Formula
Mg + F MgF₂
Ca + Cl CaCl₂
Sr + Br SrBr₂
b) Elements in group IIA have 2 electrons in their outermost shell so they can donate these electrons of group VII A which have seven electrons in their outermost shell. So it is necessary 2 elements of group VII A, each atoms accepts one electron.