1) 49.4%
Calculating the percent composition you need to first find the molar (or atomic) mass of each element individually
K = 39.09 g
O = 16 g
S = 32.06 g
K2SO3 = 158.26 g
Now, in this compound we have 2 potassiums, so we have a total of 78.18 g of potassium in this potassium sulfite, doing the math:
158.26 G = 100% (total compound mass)
78.18 = x
x = 49.4% of potassium.
2) 1.11 g
Now we have only 2.25 g of the compound, not 158.26 g, but we already know that regardless of the total mass of the potassium sulfite (K2SO3), the potassium will be responsible for 49.4% of it. Let's do the math now:
100% = 2.25g
49.4% = x grams
x = 1.11 grams of potassium.