Ionic Charges in Ammonium Metavanadate

Steps:

• Identify the ammonium ion: NH4+ has a +1 charge, as nitrogen contributes 5 valence electrons and bonds to 4 hydrogens (each +1), resulting in +1 overall.
• Confirm the formula: NH4VO3 is neutral, so the charges of NH4+ and VO3- must balance.
• Determine VO3- charge: To neutralize +1 from NH4+, VO3- must be -1.
• Verify ion notation: The formula explicitly shows NH4+ and VO3-, confirming +1 and -1 charges.

Why B is correct:

• Matches the standard charges: NH4+ is always +1 (from ammonium ion definition), and VO3- is -1 to balance the neutral compound formula.

Why the others are wrong:

• A: Incorrect charges; +2 and -2 do not match standard ion valences or formula balance.
• C: +3 exceeds ammonium's +1; unbalances the formula.
• D: +4 is impossible for NH4+; VO3- charge mismatch ignores neutrality.

Final answer: B