First, we have to find the chemical formula for zinc ion and phosphate ion.
Zinc ion is a cation, and its formula is Zn^2+,
This is because zinc atom requires 2 outer shell electrons to be removed in order to become stable.
On the other hand, phosphate ion is a anion, and its formula is PO4^3-.
In order to find the chemical formula of this ionic bond, we need to make sure their charges are balanced.
To do this, take 2+ and 3-, their least common multiple is 6, so in order to turn both charges into 6+ and 6-, we need to determine how many of that ion is needed.
So to make 2+ to 6+, we need 3 zinc ions ( +2 x 3 = 6).
And to make 3- to 6-, we need 2 phosphate ions (-3 x 2 = - 6).
Now we can just combine the chemical formulas with the number of that ion needed (you can ignore the charge)
Therefore, your answer should be Zn3(PO4)2.
Colligative properties are properties that depends on ratio of the number of solute to the number of solvent . Colligative properties are essentially solvent properties that are changed by the presence of solute . The solute particles displaces some solvent molecules in the liquid phase and therefore reduce the concentration of solvent. So basically colligative properties are independent of the nature of the solute.