Explanation:
Without even doing any calculations I would say that the 20 g HNO3 is limiting
But let us check if my opinion is correct
Balanced equation:
CaO(s) + 2HNO3 (aq) → Ca(NO3)2 (aq) + H2O(l)
1 mol CaO reacts with 2 mol HNO3
Molar mass CaO = 56 g/mol
Mol CaO in 615 g = 615 g / 56 g/mol = 10.98 mol
This will react with 10.98 * 2 = 21.96 mol HNO3
Molar mass HNO3 = 63 g/mol
Mol HNO3 in 20 g = 20 g / 63 g/mol = 0.317 mol
Clearly - my original idea correct - HNO3 is limiting .
