12) Calculate the weight of lime obtained by heating 200 kg of 90% pure limestone:

13) Decomposition of potassium chlorate gives potassium chloride and oxygen. If 4.2 moles of oxygen is needed for an experiment, how many grams of KClO₃ must be decomposed?

14) A gaseous alkane is exploded with oxygen. The volume of O₂ for complete combustion to CO₂ formed, is in the ratio 7 : 4. Deduce molecular formula of alkane.

15) 10 moles SO₂ and 15 moles O₂ were allowed to react over a suitable catalyst. 8 moles of SO₃ were formed. The remaining moles of SO₂ and O₂ are respectively:

16) If 0.5 mole of BaCl₂ is mixed with 0.2 mole of Na₃PO₄, the maximum amount of Ba₃(PO₄)₂ that can be formed is: