Which equation represents a neutralization reaction?

1. Na2CO3 + CaCl2 - > 2NaCl + CaCO3

2. NaCl + AgNO3 - > NaNO3 + AgCl

3. Ni (NO3) 2 + H2S - > NiS + 2HNO3

4. H2SO4 + Mg (OH) 2 - > MgSO4 + 2H2O

H2SO4 (aq) + Mg (OH) 2 (aq) - > MgSO4 (aq) + 2H2O (l)

Explanation:

A neutralization reaction is a chemical reaction in which the acid, (aqeous H2SO4) reacts completely with an appropriate amount of base, (aqueous Mg (OH) 2) to produce salt, (aqueous MgSO4) and water, (liquid 2H2O) only.

H2SO4 (aq) + Mg (OH) 2 (aq) - > MgSO4 (aq) + 2H2O (l)

Acid + base → Salt + Water.

During this reaction, the hydrogen ion, H+, from the H2SO4 is neutralized by the hydroxide ion, OH-, from the Mg (OH) 2 to form the water molecule, H2O.

Thus, the formation of salt, MgSO4 (aq) and water, 2H2O (l) makes it a neutralization reaction.