Question

Calculate the volume of CO2 produce at N.T.P. by heating 200 gm 25% pure limeston

Answer 1

Note the correct spelling of chemistry.

CaCO3 ==> CaO + CO2
CaCO3 available = 200 x 0.25 = 50.
mols CaCO3 = 50/molar mass CaCO3 = 50/100 = 0.5
So you will get 0.5 molsl CO2.
Plug that into PV = nRT at NTP andf solve for volume in liters.