Questions on Molecular Compounds
Multiple-Choice Questions: Molecular Compounds
1. What is a molecular compound?
A) A compound formed by ionic bonding
B) A compound made of metal atoms only
C) A compound formed by atoms sharing electrons
D) A salt made from acid-base reactions
E) A compound made of noble gases
2. Which of the following is a molecular compound?
A) NaCl
B) CO₂
C) MgO
D) KBr
E) CaF₂
3. Molecular compounds typically consist of:
A) Metals and nonmetals
B) Noble gases
C) Nonmetals only
D) Metals only
E) Metalloids only
4. Which of the following is NOT a molecular compound?
A) NH₃
B) H₂O
C) CCl₄
D) NaOH
E) CH₄
5. The bonds in a molecular compound are usually:
A) Ionic
B) Hydrogen bonds
C) Metallic
D) Covalent
E) Dipole interactions
6. Which of the following is a diatomic molecular compound?
A) CO₂
B) O₂
C) CH₄
D) NH₃
E) H₂O
7. The formula for dinitrogen pentoxide is:
A) N₂O
B) NO₂
C) N₂O₅
D) N₅O₂
E) NO₅
8. Which naming system is used for molecular compounds?
A) Stock system only
B) Prefix system (mono-, di-, tri-, etc.)
C) Roman numeral system
D) Polyatomic ion system
E) Oxidation number system
9. Which of the following prefixes corresponds to the number six?
A) Penta-
B) Tetra-
C) Hexa-
D) Hepta-
E) Octa-
10. Which compound is correctly named?
A) CO – Carbon dioxide
B) CO₂ – Carbon monoxide
C) SO₃ – Sulfur trioxide
D) N₂O₄ – Dinitrogen monoxide
E) NO – Nitrogen dioxide
11. Which of the following is a correct formula for sulfur hexafluoride?
A) S₆F
B) SF₆
C) S₂F₃
D) SF₄
E) S₃F₂
12. Which molecular compound is used in respiration and combustion?
A) CO
B) CO₂
C) O₂
D) HCl
E) CH₄
13. Which of the following is a characteristic of molecular compounds?
A) High melting point
B) Conduct electricity in molten form
C) Usually solid and hard
D) Low melting and boiling points
E) Made of metal ions
14. Molecular compounds are usually:
A) Solids with high conductivity
B) Soluble in water and conduct electricity
C) Gases, liquids, or soft solids
D) Conductive in all states
E) Metallic in appearance
15. Which of the following is a molecular compound and a greenhouse gas?
A) H₂
B) CO₂
C) NaCl
D) O₂
E) MgO
16. The compound NO₂ is named:
A) Nitrogen dioxide
B) Dinitrogen monoxide
C) Nitrogen oxide
D) Nitrate
E) Nitric oxide
17. In molecular compounds, atoms are bonded through:
A) Electron transfer
B) Shared pairs of electrons
C) Loss of protons
D) Ionic attractions
E) Metallic clouds
18. Which of the following is a binary molecular compound?
A) H₂SO₄
B) NaCl
C) CO
D) KOH
E) NH₄NO₃
19. Which element pair is most likely to form a molecular compound?
A) Na and Cl
B) Mg and O
C) C and O
D) Al and Cl
E) K and Br
20. Which of the following is a correct name–formula pair?
A) Dihydrogen monoxide – H₂O
B) Carbon tetrachloride – CCl₂
C) Sulfur dioxide – SO₃
D) Phosphorus pentachloride – PCl₃
E) Nitrogen triiodide – NI₂
21. Molecular compounds generally do NOT:
A) Form gases or liquids
B) Dissolve in water
C) Conduct electricity in solution
D) Form covalent bonds
E) Contain only nonmetals
22. The correct formula for phosphorus pentachloride is:
A) PCl₃
B) P₅Cl
C) PCl₅
D) P₅Cl₅
E) PCl₂
23. Which of the following is true about molecular compounds?
A) They always have high melting points
B) They form crystalline structures like salts
C) They are composed of ions
D) They often have low melting points
E) They conduct electricity when solid
24. Which molecule contains polar covalent bonds and is a molecular compound?
A) O₂
B) CH₄
C) NH₃
D) CCl₄
E) N₂
25. Which of the following correctly names N₂O₅?
A) Nitrogen pentoxide
B) Dinitrogen pentoxide
C) Nitrogen(V) oxide
D) Pentanitrogen dioxide
E) Nitric oxide
26. Which of the following is NOT true about molecular compounds?
A) They usually have low conductivity
B) They are made of nonmetals
C) They are formed by sharing electrons
D) They easily conduct electricity when molten
E) They can be gases at room temperature
27. The term “molecular formula” refers to:
A) A formula showing only the ions present
B) A simplified ratio of atoms
C) The actual number of atoms in a molecule
D) The same as the empirical formula
E) The weight of one mole of substance
28. Which pair of elements is least likely to form a molecular compound?
A) H and O
B) N and Cl
C) C and F
D) K and Br
E) S and O
29. Which of the following is a molecular compound used as a refrigerant?
A) CH₄
B) NH₃
C) NaCl
D) CO₂
E) O₃
30. Molecular compounds are often described as having:
A) Free-moving ions
B) Crystal lattices
C) Covalent bonds and specific shapes
D) No intermolecular forces
E) Metallic bonding
Answers with Explanations
1. C) Formed by atoms sharing electrons — covalent bonding.
2. B) CO₂ — nonmetals, covalently bonded.
3. C) Nonmetals only.
4. D) NaOH — contains metal (Na⁺), so it's ionic.
5. D) Covalent — characteristic of molecular compounds.
6. B) O₂ — diatomic and covalently bonded.
7. C) N₂O₅ — correct name and formula.
8. B) Prefix system is used (mono-, di-, tri-, etc.).
9. C) Hexa- = six.
10. C) SO₃ is sulfur trioxide.
11. B) SF₆ — sulfur hexafluoride.
12. C) O₂ — essential for combustion and respiration.
13. D) Low melting and boiling points.
14. C) Gases, liquids, or soft solids.
15. B) CO₂ — greenhouse gas and molecular.
16. A) Nitrogen dioxide.
17. B) Shared pairs of electrons.
18. C) CO — two nonmetals.
19. C) C and O — both nonmetals.
20. A) Dihydrogen monoxide = H₂O.
21. C) Conduct electricity in solution — not typical.
22. C) PCl₅ — five chlorines = pentachloride.
23. D) Low melting points.
24. C) NH₃ — polar covalent bonds.
25. B) Dinitrogen pentoxide.
26. D) They do not conduct when molten.
27. C) Actual number of atoms in a molecule.
28. D) K and Br — metal and nonmetal = ionic compound.
29. B) NH₃ — ammonia, used as a refrigerant.
30. C) Covalent bonds and specific shapes.
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