What is the concentration of a solution which contains 1 mole of CaCl2 dissolved in 2000mL of solutions?

Answer 1

In what units? molarity? molality, percent by mass? percent w/v?
For molarity, M = moles/L solution.
So M = 1 mole/2 L = 0.5 M.

Answer 2

0.5 M

Answer 3

But it's bettet to mention as 0.5 F.
F specifies formality.
Since the solute is an electrolyte or in other words calcium chloride ionize in water (dissociate), we can report the answer in 'F'.