Question

the atomic number of two elements A and B are are 19 and 20 respectively which elements ability height highest metallic property why write the molecular structure of the compounds formed when the elements combine with the element X have atomic number 17​

Answer 1

Element A is Potassium and Element B is Calcium.

Potassium will have the highest metallic property because as we go from left to right in a group of periodic table it's metallic property decrease.

Element X is Chlorine.

Molecular structure

$K^{+}$$Cl^{-}$

P.S. : I didn't understand the last one. So, I did my best. Molecular structure if you mean by that then.