Questions on Law of Multiple Proportions
Multiple-Choice Questions: Law of Multiple Proportions
1. What does the Law of Multiple Proportions state?
A) Elements can form only one compound
B) Elements always react in equal masses
C) If two elements form more than one compound, the ratios of the masses of one element combine with a fixed mass of the other in simple whole numbers
D) Mass is always conserved in a reaction
E) All compounds have the same elemental composition
2. Who is credited with formulating the Law of Multiple Proportions?
A) Antoine Lavoisier
B) John Dalton
C) Dmitri Mendeleev
D) Joseph Proust
E) Robert Boyle
3. The Law of Multiple Proportions applies to:
A) Elements forming only one compound
B) Isotopes only
C) Elements forming two or more compounds
D) Reactions involving noble gases
E) Physical mixtures
4. Which of the following pairs of compounds demonstrates the Law of Multiple Proportions?
A) H₂O and CO₂
B) CH₄ and C₂H₆
C) H₂O and H₂O₂
D) NaCl and KCl
E) O₂ and O₃
5. If 1 gram of element A combines with 2 grams and 4 grams of element B to form two different compounds, what is the ratio of masses of B combining with A?
A) 2:4
B) 4:2
C) 1:2
D) 2:1
E) 1:1
6. Which of these illustrates the Law of Multiple Proportions?
A) Water and ice
B) Carbon monoxide and carbon dioxide
C) Table salt and seawater
D) Oxygen gas and ozone
E) Sand and glass
7. The Law of Multiple Proportions supports which theory?
A) Theory of relativity
B) Bohr’s model
C) Dalton’s atomic theory
D) Quantum theory
E) Electron cloud model
8. In CO and CO₂, how do the masses of oxygen compare for the same amount of carbon?
A) 1:2
B) 2:1
C) 1:3
D) 3:2
E) 4:3
9. Why is the Law of Multiple Proportions important?
A) It helps define atomic mass
B) It supports the existence of atoms
C) It disproves the conservation of mass
D) It explains why gases expand
E) It explains phase changes
10. According to the law, the ratios of masses must be:
A) Random numbers
B) Fractions
C) Irrational numbers
D) Simple whole numbers
E) Even numbers only
11. Which law complements the Law of Multiple Proportions?
A) Law of Gravity
B) Law of Constant Composition
C) Newton’s Second Law
D) Law of Thermodynamics
E) Law of Electrical Charge
12. A compound contains 14g of nitrogen and 16g of oxygen. A second compound has 14g of nitrogen and 32g of oxygen. What is the ratio of oxygen masses?
A) 1:1
B) 1:2
C) 2:1
D) 4:1
E) 3:2
13. What is required for the Law of Multiple Proportions to apply?
A) Gases only
B) One fixed element
C) Nonmetals only
D) Identical molecular structure
E) Ionic compounds only
14. Which situation violates the Law of Multiple Proportions?
A) Two elements forming two compounds with a mass ratio of 1:1.5
B) Two compounds with non-whole number ratios
C) Two isotopes of the same element
D) Compounds with identical composition
E) One element reacting with itself
15. CO and CO₂ show a mass ratio of oxygen as:
A) 2:1
B) 1:2
C) 3:2
D) 1.33:1
E) 4:3
16. Which pair does not follow the Law of Multiple Proportions?
A) NO and NO₂
B) HCl and H₂SO₄
C) SO₂ and SO₃
D) CH₄ and C₂H₂
E) N₂O₃ and N₂O₅
17. If 1g of hydrogen forms 8g of H₂O and 16g of H₂O₂, what is the mass ratio of oxygen?
A) 2:1
B) 1:2
C) 8:16
D) 1:1
E) 16:8
18. Which scenario supports the Law of Multiple Proportions?
A) One element forming different compounds with another element in whole-number ratios
B) One element combining with two others simultaneously
C) Equal distribution of mass
D) Equal volumes of gases at STP
E) Random atomic bonding
19. What type of chemical relationship is described by the Law of Multiple Proportions?
A) Isotopic mass
B) Atomic orbitals
C) Mass ratios of elements
D) Energy levels
E) Valence electron sharing
20. The Law of Multiple Proportions is best explained using:
A) Gas laws
B) Stoichiometry
C) Atomic structure
D) Empirical formulas
E) Mass comparisons between compounds
- Questions on Atomic Theory
- Questions on Law of Conservation of Mass
- Questions on Law of Definite Proportions
Answer Key with Explanations
1. C – The law says elements combine in small whole-number ratios by mass when forming different compounds.
2. B – John Dalton formulated the law in early atomic theory.
3. C – It applies when elements form more than one compound.
4. C – H₂O and H₂O₂ show different ratios of O for the same H.
5. D – The ratio is 2:4 = 1:2 (simple whole numbers).
6. B – CO and CO₂ show a clear mass ratio of O to C.
7. C – Dalton’s atomic theory is supported by this law.
8. A – For same C, CO has 16g O; CO₂ has 32g O → 1:2 ratio.
9. B – It gives evidence that atoms exist and combine predictably.
10. D – The key is simple whole-number mass ratios.
11. B – The Law of Constant Composition says each compound has a fixed ratio; the multiple proportions law expands on this.
12. B – 16g:32g = 1:2.
13. B – One element's mass must be fixed to compare the other's variation.
14. B – Non-whole-number ratios contradict the law.
15. D – CO (12g C + 16g O); CO₂ (12g C + 32g O) → O = 16:32 = 1:2 = 1.33:1.
16. B – HCl and H₂SO₄ involve different elements entirely.
17. B – 8:16 = 1:2, a simple whole-number ratio.
18. A – That’s the essence of the law.
19. C – It’s all about how the masses of elements combine.
20. E – Comparing mass data between compounds is essential to observe the law.
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