Correct option (c) Le-Blanc
Explanation:
Le-Blanc process : It involves the following steps :
NaCl + H2SO4 → NaHSO4 + HCI
NaHSO4 + NaCl → Na2SO4+ HCI
Na2SO4 + CaCO3, + 4C → Na2CO3 + CaS + 4CONa2CO4
Na2CO3 is separated from CaS by dissolving it in water.