Questions on Binary Molecular Compounds – Naming and Formulas

Understanding the naming and formulas of binary molecular compounds is an important part of chemistry education because it helps students recognize covalent compounds and apply standardized nomenclature rules. This material is designed to support students, educators, and exam candidates through practice questions that strengthen knowledge of molecular compounds and chemical naming systems used in science and industry. As a Science Teacher and Education Specialist, I develop educational resources that connect scientific concepts with effective learning strategies.

What are Binary molecular compounds? They are formed when two nonmetals combine through covalent bonds. Their names are based on a system of prefixes that indicate the number of atoms of each element present in the compound. Learning how to name and write formulas for these compounds is fundamental to general chemistry and supports the study of chemical bonding, molecular structure, and chemical reactions. Practice questions help students master nomenclature rules and identify common molecular compounds encountered in scientific and industrial contexts.

30 Multiple-Choice Questions: Binary Molecular Compounds – Naming and Formulas

Questions

1. What is the correct name for CO?

A) Carbon oxide

B) Monocarbon monoxide

C) Carbon monoxide

D) Carbon dioxide

E) Carbon(II) oxide

2. What is the correct formula for dinitrogen pentoxide?

A) N₂O₅

B) NO₂

C) N₅O₂

D) N₂O₃

E) N₄O₅

3. What is the correct name for SO₃?

A) Sulfur trioxide

B) Sulfite

C) Sulfur trioxide oxide

D) Sulfur(III) oxide

E) Sulfur tetraoxide

4. What is the formula for carbon tetrachloride?

A) CCl₄

B) C₂Cl₄

C) CCl₂

D) CCl₃

E) C₂Cl₂

5. What is the correct name for PCl₃?

A) Phosphorus trichloride

B) Phosphorus(III) chloride

C) Phosphor trichloride

D) Triphosphorus chloride

E) Phosphorus chloride

6. What is the formula for nitrogen dioxide?

A) NO₂

B) N₂O

C) N₂O₄

D) N₂O₂

E) NO

7. What is the correct name for N₂O?

A) Nitrogen monoxide

B) Dinitrogen oxide

C) Nitrogen(II) oxide

D) Nitric oxide

E) Dinitrogen monoxide

8. What is the formula for sulfur hexafluoride?

A) SF₆

B) S₂F₆

C) SF₄

D) S₆F

E) SF₂

9. What is the correct name for Cl₂O₇?

A) Chlorine heptoxide

B) Dichlorine heptoxide

C) Chlorine(VII) oxide

D) Chlorine oxide

E) Heptachlorine oxide

10. What is the formula for tetraphosphorus decoxide?

A) P₄O₁₀

B) P₄O₈

C) PO₁₀

D) P₁₀O₄

E) P₃O₁₀

11. What is the name of BrF₅?

A) Bromine pentafluoride

B) Pentabromine fluoride

C) Bromide pentafluoride

D) Bromine fluoride

E) Bromine fluorine

12. What is the formula for dihydrogen monoxide?

A) H₂O

B) HO

C) H₂O₂

D) H₂O₃

E) H₃O₂

13. What is the name of N₂F₂?

A) Dinitrogen fluoride

B) Nitrogen difluoride

C) Dinitrogen difluoride

D) Nitrogen tetrafluoride

E) Nitrogen(II) fluoride

14. What is the formula for iodine trichloride?

A) ICl₃

B) I₃Cl

C) ICl

D) I₂Cl₃

E) ICl₂

15. What is the name of SiO₂?

A) Silicon monoxide

B) Silicon dioxide

C) Silicium oxide

D) Silicate

E) Silicon tetroxide

16. What is the formula for disulfur decafluoride?

A) S₂F₁₀

B) SF₁₀

C) S₂F₅

D) S₁₀F₂

E) S₄F₂

17. What is the name of As₂O₃?

A) Arsenic trioxide

B) Diarsenic oxide

C) Diarsenic trioxide

D) Arsenous oxide

E) Diarsenic trioxide oxide

18. What is the formula for triboron pentahydride?

A) B₃H₅

B) B₅H₃

C) BH₅

D) B₃H₂

E) B₂H₅

19. What is the name of CBr₄?

A) Carbon tetrabromide

B) Carbon bromide

C) Carbon bromine

D) Carbon(IV) bromide

E) Tetrabromocarbon

20. What is the formula for dichlorine monoxide?

A) Cl₂O

B) ClO₂

C) Cl₂O₂

D) ClO

E) Cl₃O

21. What is the name of P₂O₅?

A) Diphosphorus pentaoxide

B) Phosphorus pentoxide

C) Diphosphorus pentoxide

D) Phosphorus pentaoxide

E) Biphosphorus oxide

22. What is the formula for silicon tetrachloride?

A) SiCl₄

B) Si₄Cl

C) Si₂Cl₄

D) SiCl₂

E) Si₄Cl₄

23. What is the name of NO?

A) Nitrogen oxide

B) Nitrogen monoxide

C) Nitric oxide

D) Nitrate

E) Nitrogen(I) oxide

24. What is the formula for xenon tetrafluoride?

A) XeF₄

B) Xe₂F₄

C) XeF₂

D) Xe₄F

E) XeF₅

25. What is the name of SeCl₂?

A) Selenium chloride

B) Selenium dichloride

C) Diselenium chloride

D) Diselenium dichloride

E) Selenium(II) chloride

26. What is the formula for carbon disulfide?

A) CS₂

B) C₂S

C) CS

D) C₂S₂

E) C₂S₃

27. What is the name of N₂O₄?

A) Dinitrogen tetraoxide

B) Nitrogen tetroxide

C) Nitrogen dioxide

D) Nitrogen(IV) oxide

E) Dinitrogen dioxide

28. What is the formula for phosphorus triiodide?

A) PI₃

B) P₃I

C) P₃I₃

D) PI₂

E) PI₄

29. What is the name of BCl₃?

A) Boron chloride

B) Boron trichloride

C) Triboron chloride

D) Trichloroboron

E) Boron(III) chloride

30. What is the formula for diboron tetrahydride?

A) B₂H₄

B) BH₄

C) B₄H₂

D) B₂H₂

E) B₄H₄

Answers with Explanations

1. C) Carbon monoxide – One oxygen requires “mono” prefix.

2. A) N₂O₅ – "Di" = 2 nitrogen, "penta" = 5 oxygen.

3. A) Sulfur trioxide – SO₃ → 1 sulfur, 3 oxygen.

4. A) CCl₄ – One carbon and 4 chlorine atoms.

5. A) Phosphorus trichloride – 1 P, 3 Cl → use “tri”.

6. A) NO₂ – One N, 2 O = nitrogen dioxide.

7. E) Dinitrogen monoxide – N₂O = 2 N, 1 O.

8. A) SF₆ – 1 S, 6 F → sulfur hexafluoride.

9. B) Dichlorine heptoxide – 2 Cl, 7 O.

10. A) P₄O₁₀ – 4 phosphorus, 10 oxygen atoms.

11. A) Bromine pentafluoride – 1 Br, 5 F.

12. A) H₂O – dihydrogen = 2 H, mono = 1 O.

13. C) Dinitrogen difluoride – N₂F₂.

14. A) ICl₃ – 1 I, 3 Cl → iodine trichloride.

15. B) Silicon dioxide – SiO₂.

16. A) S₂F₁₀ – di = 2 S, deca = 10 F.

17. C) Diarsenic trioxide – As₂O₃.

18. A) B₃H₅ – tri = 3 B, penta = 5 H.

19. A) Carbon tetrabromide – CBr₄.

20. A) Cl₂O – dichlorine monoxide.

21. C) Diphosphorus pentoxide – P₂O₅.

22. A) SiCl₄ – one Si, 4 Cl.

23. B) Nitrogen monoxide – NO.

24. A) XeF₄ – xenon tetrafluoride.

25. B) Selenium dichloride – SeCl₂.

26. A) CS₂ – 1 carbon, 2 sulfur atoms.

27. A) Dinitrogen tetraoxide – N₂O₄.

28. A) PI₃ – 1 phosphorus, 3 iodine atoms.

29. B) Boron trichloride – BCl₃.

30. A) B₂H₄ – 2 B, 4 H.

Questions on Binary Molecular Compounds – Naming and Formulas

Practical Classroom Applications

• Introduce Covalent Bonding

Explain how nonmetal atoms share electrons to form molecular compounds.

• Practice Prefix Rules

Teach students how prefixes such as mono-, di-, tri-, tetra-, and penta- are used in chemical nomenclature.

• Formula-Writing Activities

Have students convert compound names into chemical formulas and vice versa.

• Compare Ionic and Molecular Compounds

Highlight the differences between covalent and ionic bonding using examples.

• Build Molecular Models

Use physical or digital models to visualize the structure of common binary molecular compounds.

• Explore Real-World Examples

Discuss compounds such as carbon dioxide, sulfur dioxide, and nitrogen monoxide and their importance in nature and industry.

• Reinforce Scientific Vocabulary

Strengthen students' understanding of chemistry terminology and naming conventions.

• Support Exam Preparation

Use the questions as review material for middle school, high school, AP Chemistry, and introductory college chemistry courses.

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

Questions on Binary Molecular Compounds – Naming and Formulas