Answer:-
B) CaCl2 + Li2CO3 --> CaCO3 + 2LiCl
D) 2MgI2 + Mn(SO3)2 ---> 2MgSO3 + MnI4
Explanation:-
For a reaction to be double displacement reaction there are two things we need to look for
1) There must be an interchange of the group of ions
2) The reactants must dissolve in water to release ions
In this question every option shows an interchange of ions. So we must use the second criteria to find out which one is not a double displacement reaction.
In case of B the two reactants are CaCl2 and Li2CO3.
Li2CO3 does not form ions on dissolving in water. It is because carbonate salts are not soluble in water.
Hence B) CaCl2 + Li2CO3 --> CaCO3 + 2LiCl is not a double displacement reaction.
In case of D the two reactants are MgI2 and Mn(SO3)2.
Mn(SO3)2 does not form ions on dissolving in water. It is because sulphite salt of metals except potassium and sodium are not soluble in water.
Hence D) 2MgI2 + Mn(SO3)2 ---> 2MgSO3 + MnI4 is not a double displacement reaction.
