The main gases leaving the lime kiln are nitrogen and carbon dioxide explain why???? I don't understand

Question

anonymous · Answer

It's a bit late but it's due tomorrow and I'm really stuck

anonymous · Answer

well i looked up lime kiln and it is basically a giant oven that you put lime(CaCO_3) into and the heat causes the lime to break down into CaO and CO_2(Carbon Dioxide). 
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this is the chemical equation CaCO3 + heat → CaO + CO2
so basically the reaction releases carbon dioxide...which is a gas and comes out of the lime kiln smoke stack i guess. I dont know about the nitrogen though