Calomel is:
As we learnt in
Reaction with Mercury (I) Chloride with Chlorine -
- wherein
Cl2 oxidise Hg22+ into Hg2+
Calomel is Mercury (I) chloride with the formula Hg2Cl2. It was earlier used in medicine as a laxative.
Option 1)
This answer is incorrect
Option 2)
This answer is incorrect
Option 3)
This answer is incorrect
Option 4)
This answer is correct