Question

4 g of cao is formed by decopmposition of caco3 then what is the amount of caco3 taken

Answer 1

Rxn involved -

      CaCO3 →  CaO +  CO2

moles of CaO formed  =  4/ 56 = 0.071

and from the rxn it is clear that 1 mole of CaO is produced by 1 mole of CaCO3

Hence amt of CaCO3 req. =  0.071 × 100  =  7.1 gm

hope this helps