Question

100 gm of mixture caco3 and na2co3 was ignited which forms 11.2 l of co2 at stp then the mass ratio na2co3 in the mixture will be

Answer 1

na2co3 does not get decomposed due to ignition.
    caco3 decomposes to form cao and co2  
       1 mol                                                  1 mol
 i.e. 1 mol of caco3 gives 22.4 l of co2

moles of caco3 in 11.2 l pf co2 is 0.5g

mass of caco3= 0.5*100 =50g
therefore in mixture consists of 50g of caco3 and 50g of na2co3 (100-50)which does not decompose.so the ratio is 1:1