Electron count in NH3 and NH4+

Steps:

• Identify ammonia as NH3 (neutral molecule) and ammonium as NH4+ (cation from protonation).
• Calculate total electrons: NH3 has 7 (N) + 3×1 (H) = 10 electrons.
• For NH4+, atomic electrons total 7 + 4×1 = 11, but +1 charge removes 1 electron, yielding 10 electrons.
• Confirm only option C matches this equivalence.

Why C is correct:

• NH4+ forms by NH3 accepting H+ via dative bond, preserving total electron count at 10 (NH3: 7+3=10; NH4+: 11-1=10).

Why the others are wrong:

• A: NH4+ with strong acid forms NH4+ salt; ammonia gas evolves from NH4+ with strong base (e.g., OH-).
• B: AgI is insoluble in concentrated NH3, unlike AgCl which forms [Ag(NH3)2]+ complex.
• D: NH4+ is tetrahedral (sp3 hybridization), not square planar; it has one dative bond but no d orbitals involved.

Final answer: C