Question

An element X (atomic number 17) reacts with an element Y (atomic number 12) to form a divalent halide. Where do X and Y are placed in the modern periodic table? (mention the group and period of each)

Answer 1

Element with atomic number 17 $i.e$ $X$ is $Chlorine$ it belongs to period 3 and group 17(VII A). Element with atomic number 12 $i.e$ $Y$ is $Magnesium$ and it belongs to period 3 and group 2(IIA).

Magnesium forms a divalent halide $MgC{l}_2$ with chlorine.