Calcium carbonate, caco3(s), decomposes upon heating to give cao(s) and co2(g). a sample of caco3 is decomposed, and the carbon dioxide is collected in a sealed 250 ml flask. after the decomposition is complete, the gas has a pressure of 1.7 atm at a temperature of 31°c. how many moles of co2 gas were generated?

The  moles of  CO2  gas  generated is calculated using  ideal  gas  equation
that is PV=nRT  where n is number  of  moles
P= 1.7 atm
V=  250 ml =  250/1000= 0.25 L
R(gas constant)= 0.0821 L.atm/mol.K (always  given)
T =  31 +273=304 k

by  making n  the subject  of the  formula   n=PV/RT

n=( 1.7 atm  x  0.25 L)/( 0.0821 L.atm/k.mol x304K)  =  0.017  moles