Question

Ca-->CaS-->CaCl2-->Ca(NO3)2-->CaSo4-->CaS

Answer 1

Ca+S=CaS
CaS+2KCl=CaCl2+K2S
CaCl2+Ba(NO3)2=Ca(NO3)2+BaCl2
CaNO3+Na2SO4=CaSO4+NaNO3
CaSO4+CuS=CaS+CuSO4

Answer 2

ca+s->cas
cas+zncl->cacl2+zns
cacl2+agno3->agcl+ca(no3)2
ca(no3)2+k2so4->caso4+kno3
caso4+nas->cas+na2so4