I know it would be calcium chloride, not sure why. Maybe someone could answer that part.
The answer I believe is genus
Group 12 Elements have two valence electrons while Group 13 Elements have three valence electrons.
Number of valence electrons tend to determine factors like reactivity. So elements with different number of valence electrons will have different properties.
That is why G12 and G13 have different properties
You didn’t post the photo or full question