In which of the following bond angles is maximum?
(A) NH3

(B) NH4+

(C) PCl3

(D) SCl2

Let's analyze the bond angles for each of the given molecules:

(A) NH₃ (Ammonia): In NH₃, the central nitrogen atom is bonded to three hydrogen atoms, resulting in a trigonal pyramidal molecular geometry. The ideal bond angle for this geometry is 107 degrees.

(B) NH₄⁺ (Ammonium ion): In NH₄⁺, the central nitrogen atom is bonded to four hydrogen atoms, forming a tetrahedral molecular geometry. The ideal bond angle for this geometry is 109.5 degrees.

(C) PCl₃ (Phosphorus trichloride): In PCl₃, the central phosphorus atom is bonded to three chlorine atoms, resulting in a trigonal pyramidal molecular geometry. The ideal bond angle for this geometry is also 107 degrees.

(D) SCl₂ (Sulfur dichloride): In SCl₂, the central sulfur atom is bonded to two chlorine atoms, resulting in a bent molecular geometry. The ideal bond angle for this geometry is around 104.5 degrees.

Comparing the given options, we find that the maximum bond angle is in option (B) NH₄⁺, with a bond angle of 109.5 degrees, characteristic of a tetrahedral molecular geometry. Therefore, the correct answer is (B) NH₄⁺.