Polyatomic Ions: Questions on Naming and Formulas

Questions on Polyatomic Ions – Naming and Formulas

Understanding the naming and formulas of polyatomic ions is essential for mastering ionic compounds, chemical reactions, and nomenclature systems used throughout chemistry. This material is designed to support students, educators, and exam candidates by providing practice opportunities that strengthen knowledge of common polyatomic ions and their applications in scientific and industrial contexts.


30 Multiple-Choice Questions: Polyatomic Ions – Naming and Formulas


  Identification and Naming

    1. What is the correct name for NO₃⁻?

A) Nitrite

B) Nitrate

C) Nitride

D) Nitroxide

E) Nitrosyl

    2. What is the name of SO₄²⁻?

A) Sulfate

B) Sulfite

C) Sulfide

D) Sulfoxide

E) Disulfate

    3. What is the correct name for NH₄⁺?

A) Ammonium

B) Ammonia

C) Aminium

D) Azanium

E) Nitronium

    4. What is the correct name for CO₃²⁻?

A) Carbonite

B) Carbonyl

C) Carbonate

D) Carboxide

E) Carbyne

    5. What is the name of PO₄³⁻?

A) Phosphide

B) Phosphate

C) Phosphite

D) Perphosphate

E) Hypophosphate

    6. What is the name of ClO₃⁻?

A) Chlorate

B) Chlorite

C) Hypochlorite

D) Perchlorate

E) Chlorine oxide

    7. What is the name of NO₂⁻?

A) Nitrate

B) Nitride

C) Nitrite

D) Nitrosate

E) Nitrile

    8. What is the name of SO₃²⁻?

A) Sulfur trioxide

B) Sulfite

C) Sulfate

D) Disulfide

E) Sulfoxide

    9. What is the correct name for OH⁻?

A) Hydroxide

B) Hydride

C) Hydronium

D) Hydrogenate

E) Oxide

    10. What is the name of MnO₄⁻?

A) Manganate

B) Permanganate

C) Manganese oxide

D) Tetramanganate

E) Manganoxide


🧪 Writing Formulas

    11. What is the formula for sulfate?

A) SO₃²⁻

B) SO₄²⁻

C) S₂O₇²⁻

D) HSO₄⁻

E) S₄O₄²⁻

    12. What is the formula for ammonium?

A) NH₃

B) NH₂⁻

C) NH₄⁺

D) NH₄⁻

E) HN₄⁺

    13. What is the correct formula for phosphate?

A) PO₃³⁻

B) PO₄²⁻

C) PO₄³⁻

D) P₂O₅³⁻

E) P₃O₄³⁻

    14. What is the formula for acetate?

A) CH₃CO₂⁻

B) C₂H₃O₂⁻

C) CH₃COO⁻

D) All of the above

E) None of the above

    15. What is the formula for chromate?

A) CrO₂⁻

B) CrO₄²⁻

C) Cr₂O₇²⁻

D) Cr₂O₄²⁻

E) Cr(OH)₄⁻


🧪 Naming Compounds Containing Polyatomic Ions

    16. What is the name of NaNO₃?

A) Sodium nitrate

B) Sodium nitrite

C) Sodium nitric acid

D) Sodium nitrogenate

E) Sodium nitride

    17. What is the correct name for CaCO₃?

A) Calcium carbonate

B) Calcium oxide

C) Calcium bicarbonate

D) Calcium hydroxide

E) Calcium carbite

    18. What is the name of NH₄Cl?

A) Ammonia chloride

B) Ammonium chloride

C) Azanium chloride

D) Ammonium chlorate

E) Ammonium perchlorate

    19. What is the name of KNO₂?

A) Potassium nitrate

B) Potassium nitrite

C) Potassium nitrogen

D) Potassium ammonia

E) Potassium azide

    20. What is the name of Fe(NO₃)₃?

A) Iron nitrate

B) Iron(III) nitrate

C) Iron trinitrate

D) Iron nitride

E) Iron(II) nitrate


🧪 More Complex Examples

    21. What is the name of Ba(OH)₂?

A) Barium oxide

B) Barium hydroxide

C) Barium peroxide

D) Barium hydrate

E) Barium hydride

    22. What is the formula for potassium sulfate?

A) KSO₄

B) K₂SO₄

C) KSO₃

D) K₂SO₃

E) K₃SO₄

    23. What is the name of Na₂SO₃?

A) Sodium sulfate

B) Disodium sulfate

C) Sodium sulfite

D) Sodium sulfoxide

E) Sodium sulfur

    24. What is the name of Cu(NO₂)₂?

A) Copper(II) nitrate

B) Copper nitride

C) Copper(II) nitrite

D) Copper nitrosyl

E) Copper nitrate

    25. What is the formula for aluminum acetate?

A) Al(CH₃COO)₂

B) Al₃C₂H₃O₂

C) Al(CH₃COO)₃

D) Al₂(C₂H₃O₂)₃

E) Al(CO₂CH₃)₃


🧪 Mixed Concept Questions

    26. Which of these ions has a -1 charge?

A) SO₄²⁻

B) PO₄³⁻

C) OH⁻

D) CO₃²⁻

E) CrO₄²⁻

    27. What is the charge on the phosphate ion?

A) -1

B) -2

C) -3

D) +1

E) +3

    28. What is the charge on the ammonium ion?

A) -1

B) 0

C) +1

D) +2

E) -2

    29. What is the name of the polyatomic ion HCO₃⁻?

A) Carbonate

B) Bicarbonate

C) Hydrogen carbonate

D) Both B and C

E) Carbonous acid

    30. What is the formula for permanganate?

A) MnO₂⁻

B) MnO₄⁻

C) MnO₄²⁻

D) Mn₂O₇

E) MnO



  Answers with Explanations

    1. B – NO₃⁻ is nitrate.

    2. A – SO₄²⁻ is sulfate.

    3. A – NH₄⁺ is ammonium.

    4. C – CO₃²⁻ is carbonate.

    5. B – PO₄³⁻ is phosphate.

    6. A – ClO₃⁻ is chlorate.

    7. C – NO₂⁻ is nitrite.

    8. B – SO₃²⁻ is sulfite.

    9. A – OH⁻ is hydroxide.

    10. B – MnO₄⁻ is permanganate.

    11. B – Sulfate is SO₄²⁻.

    12. C – Ammonium is NH₄⁺.

    13. C – Phosphate is PO₄³⁻.

    14. D – Acetate can be written as CH₃COO⁻, CH₃CO₂⁻, or C₂H₃O₂⁻.

    15. B – Chromate is CrO₄²⁻.

    16. A – NaNO₃ is sodium nitrate.

    17. A – CaCO₃ is calcium carbonate.

    18. B – NH₄Cl is ammonium chloride.

    19. B – KNO₂ is potassium nitrite.

    20. B – Fe(NO₃)₃ is iron(III) nitrate.

    21. B – Ba(OH)₂ is barium hydroxide.

    22. B – Potassium (K⁺) and sulfate (SO₄²⁻) → K₂SO₄.

    23. C – Na₂SO₃ is sodium sulfite.

    24. C – Cu(NO₂)₂ is copper(II) nitrite.

    25. C – Aluminum (Al³⁺) and acetate (CH₃COO⁻) → Al(CH₃COO)₃.

    26. C – OH⁻ has a -1 charge.

    27. C – Phosphate has a -3 charge.

    28. C – Ammonium has a +1 charge.

    29. D – HCO₃⁻ is called both bicarbonate and hydrogen carbonate.

    30. B – Permanganate is MnO₄⁻.



Practical Classroom Applications

• Introduce Common Polyatomic Ions

Teach students the formulas and charges of ions such as nitrate, sulfate, carbonate, phosphate, hydroxide, and ammonium.

• Create Polyatomic Ion Charts

Develop reference tables that help students identify patterns and memorize formulas.

• Practice Naming and Formula Writing

Encourage students to convert ion names into formulas and formulas into names.

• Build Compound Formation Activities

Combine polyatomic ions with cations to create ionic compounds and reinforce charge balancing.

• Explore Environmental Applications

Discuss the importance of nitrates and phosphates in ecosystems, agriculture, and water quality.

• Connect to Industrial Chemistry

Examine how polyatomic ions are involved in fertilizers, detergents, pharmaceuticals, and manufacturing processes.

• Strengthen Scientific Vocabulary

Reinforce chemistry terminology used in laboratories and advanced science courses.

• Prepare for Exams

Use the questions for review sessions in middle school, high school, AP Chemistry, and introductory college chemistry classes.

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Ronaldo Silva: Professor and Specialist in Science Education from University Federal FLuminense/RJ, with over 25 years of teaching experience..

 
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