Explanation:

n = moles of compound
V =Volume of the solution in Liters
Moles of potassium sulfate ,n= 
Volume of the solution = 1.50 L
Molarity of the solution = 
Molarity of potassium sulfate solution:
![[K_2SO_4]=M=6.8965\times 10^{-7} mol/L](https://tex.z-dn.net/?f=%5BK_2SO_4%5D%3DM%3D6.8965%5Ctimes%2010%5E%7B-7%7D%20mol%2FL)
1 mole of potassium sulfate gives 2 moles of potassium ions and 1 mole of sulfate ions.
Molarity of potassium ions in the solution:
![[K^+]=2\times M=2\times 6.8965\times 10^{-7} mol/L=1.3793\times 10^{-6} mol/L](https://tex.z-dn.net/?f=%5BK%5E%2B%5D%3D2%5Ctimes%20M%3D2%5Ctimes%206.8965%5Ctimes%2010%5E%7B-7%7D%20mol%2FL%3D1.3793%5Ctimes%2010%5E%7B-6%7D%20mol%2FL)
Molarity of sulfate ions in the solution:
![[SO_4^{2-}]=1\times 6.8965\times 10^{-7} mol/L=6.8965\times 10^{-7} mol/L](https://tex.z-dn.net/?f=%5BSO_4%5E%7B2-%7D%5D%3D1%5Ctimes%206.8965%5Ctimes%2010%5E%7B-7%7D%20mol%2FL%3D6.8965%5Ctimes%2010%5E%7B-7%7D%20mol%2FL)
Concentration in ppm:
ppm = Milligram of compo present in 1 liter solution.
ppm = Molarity × Molar mass of compound × 1000
Concentration of potassium ion in ppm:

![[K^+]=0.05517 ppm](https://tex.z-dn.net/?f=%5BK%5E%2B%5D%3D0.05517%20ppm)
Concentration of sulfate ions in ppm:

![[SO_4^{2-}]=0.06620 ppm](https://tex.z-dn.net/?f=%5BSO_4%5E%7B2-%7D%5D%3D0.06620%20ppm)