Question

how many moles of potassium would you need to prepare 1200 grams of 5.0% potassium sulfate (m/m) solution

Answer 1

The  moles  of  potassium  that  you  would    need  to  prepare  1200 g  of  5% potassium   sulfate solution  is    1.538 moles

calculation
  calculate  the mass  potassium using  the below formula

%M/M =  mass  of the  solute(potassium)/mass of the  solvent (potassium  sulfate solution)

let  the  mass  of  potassium be represented by  Y

then  convert %  into fraction  = 5/100

5/100 =  Y/1200
cross  multiplication
100y =  6000
divide  both side by 100

Y=  60 g

moles of potassium =mass/molar  mass

= 60/39=1.538