To completely neutralize a solution containing 28 g of potassium hydroxide, a volume of sulfur (IV) oxide is needed.

2KOH + SO2 = K2SO4 + H2.
1) According to the periodic table, we calculate the molar mass of potassium hydroxide: 39 + 1 + 16 = 56.
2) Find the amount of potassium hydroxide substance. To do this, divide the mass of the hydroxide by its molar mass: 28/56 = 0.5 mol.
3) According to the reaction equation, there is one mole of sulfur oxide for two moles of potassium hydroxide. This means that the amount of sulfur oxide substance is: 2 * 0.5 = 1 mol.
4) Find the volume of sulfur oxide. To do this, we multiply the amount of oxide substance by the molar volume: 1 * 22.4 = 22.4 liters – the answer.