The missing compounds are X1 being Cu(OH)2 and X2 being CuCO3.
So the complete sequences for each element are:
Cu—>CuCl2—>Cu—>CuO—>CuSo4—>Cu(OH)2—>CuCO3
Ca—>Ca(OH)2—>CaCO3—>CaCl2
The missing compounds are X1 being Cu(OH)2 and X2 being CuCO3.
So the complete sequences for each element are:
Cu—>CuCl2—>Cu—>CuO—>CuSo4—>Cu(OH)2—>CuCO3
Ca—>Ca(OH)2—>CaCO3—>CaCl2