Question

20.2 g of potassium phosphate is dissolved into 650 ml of H2O

Answer 1

That's a statement, not a question. You want to know what?

Answer 2

20.2 g of potassium phosphate is dissolved into 650 ml of H2O
yes i so confuse i need to know what property is if is morality , osmolarity , boiling point or if are another property? thank you.

Answer 3

It's a property that it dissolves in water. One can calculate molality (note it isn't morality --these solutions have no moral character).
The definition is m = moles/kg solvent.
moles = grams/molar mass.
Solve for moles first, then substitute into m = moles/kg and solve for molality.