Questions on Molecular Formula
Multiple-Choice Questions: Molecular Formula
Basic Understanding
1. What does a molecular formula represent?
A) The number of atoms in a crystal lattice
B) The structure of a molecule
C) The types and numbers of atoms in a molecule
D) The oxidation states of elements
E) The physical state of a substance
2. Which of the following is a correct molecular formula for water?
A) H
B) HO
C) H₂O
D) OH₂
E) H₂
3. Which molecular formula represents carbon dioxide?
A) CO
B) CO₂
C) C₂O
D) C₂O₂
E) OC
4. What is the molecular formula of methane?
A) CH₂
B) CH₄
C) C₂H₂
D) C₂H₆
E) CH₃
5. Which molecular formula corresponds to ozone?
A) O₂
B) O₃
C) O
D) O₄
E) OO
🔹 Identifying Formulas
6. What is the molecular formula for glucose?
A) C₆H₁₂O₆
B) C₆H₆
C) CH₃COOH
D) C₂H₆O
E) C₁₂H₂₂O₁₁
7. Which of the following is a molecular formula for hydrogen peroxide?
A) H₂O₂
B) HO
C) H₂O
D) H₃O
E) OH
8. Which compound has the molecular formula NH₃?
A) Nitrous oxide
B) Nitric acid
C) Ammonia
D) Ammonium
E) Nitrogen dioxide
9. Which of these formulas represents a molecule with two hydrogen atoms and two oxygen atoms?
A) H₂O
B) H₂O₂
C) H₂O₃
D) HO
E) H₂O₄
10. Which of these is a diatomic molecule?
A) CO₂
B) NO₂
C) O₂
D) C₂H₄
E) H₂O
🔹 Analysis and Application
11. Which of these molecular formulas represents ethane?
A) C₂H₂
B) C₂H₆
C) C₂H₄
D) CH₄
E) CH₃
12. The molecular formula HCl indicates a molecule made of:
A) Hydrogen and lithium
B) Hydrogen and carbon
C) Hydrogen and chlorine
D) Helium and chlorine
E) Hydrogen and cobalt
13. The molecular formula N₂ tells us that the molecule contains:
A) 2 atoms of nitrogen bonded together
B) 2 neutrons
C) 1 nitrogen atom and 2 hydrogen atoms
D) 2 nitrogen molecules
E) 1 nitrogen atom
14. Which of the following has the same empirical and molecular formula?
A) C₂H₆
B) C₂H₄O₂
C) H₂O
D) C₆H₁₂O₆
E) C₄H₁₀
15. Which of the following formulas represents a molecule of propane?
A) C₂H₄
B) C₃H₈
C) C₄H₁₀
D) CH₄
E) C₃H₆
🔹 Mixed Review
16. The molecular formula for nitric acid is:
A) HNO₂
B) HNO₃
C) NO₃
D) NH₃
E) HNO₄
17. Which of the following is the molecular formula for ethanol?
A) C₂H₆O
B) CH₃OH
C) C₃H₈O
D) CH₄O
E) C₂H₄O₂
18. Which formula correctly represents dinitrogen tetroxide?
A) NO₄
B) N₂O₄
C) N₄O₂
D) N₂O₂
E) NO₂
19. Which molecule is represented by the formula C₆H₆?
A) Glucose
B) Benzene
C) Ethanol
D) Acetylene
E) Methane
20. A molecule with the formula C₃H₆O is likely:
A) Acetone
B) Glucose
C) Propane
D) Methanol
E) Carbon dioxide
Answers with Explanations
1. C – A molecular formula shows the types and exact numbers of atoms in a molecule.
2. C – Water is H₂O: two hydrogen atoms and one oxygen atom.
3. B – CO₂ represents carbon dioxide: one carbon and two oxygen atoms.
4. B – Methane is CH₄: one carbon and four hydrogen atoms.
5. B – Ozone is made of three oxygen atoms: O₃.
6. A – Glucose has the molecular formula C₆H₁₂O₆.
7. A – Hydrogen peroxide is H₂O₂.
8. C – Ammonia is NH₃: one nitrogen and three hydrogen atoms.
9. B – H₂O₂ is the formula for hydrogen peroxide.
10. C – O₂ is a diatomic molecule with two oxygen atoms.
11. B – Ethane is C₂H₆: two carbon and six hydrogen atoms.
12. C – HCl consists of one hydrogen and one chlorine atom.
13. A – N₂ means two nitrogen atoms bonded together.
14. C – H₂O's molecular and empirical formulas are the same.
15. B – Propane is C₃H₈.
16. B – Nitric acid is HNO₃.
17. A – Ethanol is C₂H₆O.
18. B – Dinitrogen tetroxide = N₂O₄.
19. B – Benzene has the formula C₆H₆.
20. A – C₃H₆O is the molecular formula of acetone (or propanal).
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