See image — AITS & Test Series Chemistry Question

💡 Solution & Explanation

Let the maximum limiting labelling of oleum is (100 + x)% In 100 gram of oleum the maximum mass of free SO3 should be tending to 100 gram and hence, the mass of water needed x gram, should be exactly that mass which combine completely with all the free SO3 present 2 3 2 4 H O SO H SO   100 x 18 80   = 22.5