Question

What is the formula of the compound when 'X' with atomic number 12 combines with an
element 'Y' with atomic number 17? ​

Answer 1

Answer:

Elements :- X Y

Valency / charge :- 2 1

Using cross multiplication :- XY

2

Answer 2

Answer:

We know that the element with atomic number 12 is Magnesium and the one with atomic number 17 is Chlorine.

Thus, Mg and Cl will react to form MgCl2, since valency of Mg is 2 and that of Cl is 1.