To determine which reaction is a neutralization reaction, we need to identify the characteristics of a neutralization reaction. A neutralization reaction generally occurs between an acid and a base to produce a salt and water.
Let's analyze each option in detail:
### Option A
[tex]\[ 2\ NaOH\ (aq) + MgCl_2\ (aq) \rightarrow Mg(OH)_2\ (s) + 2\ Na^+\ (aq) + 2\ Cl^-\ (aq) \][/tex]
This reaction is a double displacement reaction between sodium hydroxide (a base) and magnesium chloride (a salt), resulting in magnesium hydroxide (a precipitate) and sodium and chloride ions in solution. It is not a neutralization reaction since it does not produce water and a salt.
### Option B
[tex]\[ HNO_3\ (aq) + LiOH\ (aq) \rightarrow H_2O\ (l) + LiNO_3\ (aq) \][/tex]
This reaction involves nitric acid (HNO_3) and lithium hydroxide (LiOH). Here, the acid (HNO_3) reacts with the base (LiOH) to produce water (H_2O) and a salt (LiNO_3). This fits the definition of a neutralization reaction perfectly.
### Option C
[tex]\[ 4\ Fe\ (s) + 3\ O_2\ (g) \rightarrow 2\ Fe_2O_3\ (s) \][/tex]
This reaction is a synthesis reaction where iron combines with oxygen to form iron(III) oxide. It does not involve an acid and a base and does not produce water, so it is not a neutralization reaction.
### Option D
[tex]\[ ZnCl_2\ (aq) + CaCrO_4\ (aq) \rightarrow ZnCrO_4\ (s) + CaCl_2\ (aq) \][/tex]
This reaction is another example of a double displacement reaction, resulting in the formation of zinc chromate (a precipitate) and calcium chloride in solution. It is not a neutralization reaction because it does not involve an acid and a base producing water and a salt.
Therefore, the reaction that is a neutralization reaction is:
[tex]\[ \text{Option B: } HNO_3\ (aq) + LiOH\ (aq) \rightarrow H_2O\ (l) + LiNO_3\ (aq) \][/tex]
