Questions on Dalton’s Atomic Theory
20 Multiple-Choice Questions: Dalton’s Atomic Theory
1. Who proposed the first modern atomic theory?
A) J.J. Thomson
B) Ernest Rutherford
C) John Dalton
D) Niels Bohr
E) Democritus
2. Dalton’s atomic theory was proposed in which century?
A) 16th
B) 17th
C) 18th
D) 19th
E) 20th
3. According to Dalton, all matter is composed of:
A) Protons
B) Neutrons
C) Molecules
D) Atoms
E) Elements
4. Dalton stated that atoms of a given element are:
A) Different in mass and properties
B) Identical in mass and properties
C) Always unstable
D) Composed of electrons
E) Formed in chemical reactions
5. Which of the following is not a postulate of Dalton’s theory?
A) All matter is made of indivisible atoms
B) Atoms cannot be created or destroyed
C) Atoms can transform into energy
D) Atoms of different elements combine in fixed ratios
E) Chemical reactions involve the rearrangement of atoms
6. According to Dalton, atoms combine in:
A) Any ratio
B) No specific ratio
C) Fixed, simple whole-number ratios
D) Complex fractional ratios
E) Unlimited ratios
7. Dalton’s theory helped explain which fundamental law?
A) Law of Reflection
B) Law of Inertia
C) Law of Definite Proportions
D) Law of Gravity
E) Law of Universal Gravitation
8. Which experiment directly contradicted Dalton's idea that atoms are indivisible?
A) Rutherford’s Gold Foil
B) Millikan’s Oil Drop
C) Thomson’s Cathode Ray
D) Bohr’s Hydrogen Spectrum
E) Avogadro’s Hypothesis
9. Which subatomic particle was discovered after Dalton’s theory?
A) Photon
B) Atom
C) Electron
D) Positron
E) Quark
10. Dalton’s atomic theory contributed to the understanding of:
A) Quantum mechanics
B) Conservation of energy
C) Periodic table
D) Chemical reactions
E) Blackbody radiation
11. According to Dalton, in a chemical reaction:
A) Atoms are created
B) Atoms are destroyed
C) Atoms are rearranged
D) Atoms change their identity
E) Atoms turn into energy
12. Which law does Dalton's theory support regarding fixed composition of compounds?
A) Law of Conservation of Energy
B) Law of Thermodynamics
C) Law of Definite Proportions
D) Law of Increasing Entropy
E) Law of Motion
13. Which part of Dalton’s theory is now considered incorrect?
A) All matter is made of atoms
B) Atoms of the same element are identical
C) Atoms combine in whole-number ratios
D) Chemical reactions involve rearrangement of atoms
E) Atoms cannot be subdivided
14. Dalton believed that atoms of different elements have:
A) The same mass
B) Different masses
C) Identical charges
D) No volume
E) Different orbits
15. Dalton’s atomic theory helped introduce the concept of:
A) Isotopes
B) Atomic structure
C) Atomic mass
D) Radioactivity
E) Relativity
16. In Dalton’s model, atoms are represented as:
A) Electrons orbiting a nucleus
B) Indivisible spheres
C) Nucleus with protons
D) Clouds of probability
E) Tiny magnets
17. Dalton's theory supports which conservation law?
A) Conservation of Motion
B) Conservation of Energy
C) Conservation of Volume
D) Conservation of Mass
E) Conservation of Charge
18. Dalton's atomic theory could not explain:
A) Why matter exists
B) The nature of light
C) The structure of atoms
D) Isotopes of an element
E) Chemical reactions
19. The concept that atoms are rearranged in reactions but not changed into other atoms supports:
A) Law of Constant Acceleration
B) Law of Conservation of Mass
C) Law of Universal Gravitation
D) Law of Reflection
E) Law of Fluid Motion
20. Which scientist’s findings modified Dalton’s theory by discovering electrons?
A) Niels Bohr
B) Albert Einstein
C) James Chadwick
D) J.J. Thomson
E) Ernest Rutherford
- Questions on Law of Conservation of Mass
- Questions on Law of Multiple Proportions
- Questions on Law of Definite Proportions
- Questions on Mass Ratio Calculation
Answer Key with Explanations
1. C – John Dalton proposed the first modern atomic theory.
2. D – Dalton presented his theory in the early 19th century (1803).
3. D – All matter is made of atoms according to Dalton.
4. B – Atoms of the same element are identical in mass and properties.
5. C – Atoms turning into energy is not part of Dalton’s theory.
6. C – Atoms combine in fixed, whole-number ratios to form compounds.
7. C – The Law of Definite Proportions is explained by Dalton’s theory.
8. C – Thomson’s experiment showed atoms are divisible (discovered electrons).
9. C – Electrons were discovered by Thomson after Dalton’s theory.
10. D – Dalton’s theory contributed to understanding chemical reactions.
11. C – Dalton said atoms are rearranged during chemical reactions.
12. C – Law of Definite Proportions: compounds have constant composition.
13. B – Isotopes show that atoms of the same element can differ in mass.
14. B – Different elements have atoms with different masses.
15. C – Dalton helped introduce the idea of atomic mass.
16. B – He modeled atoms as indivisible solid spheres.
17. D – Dalton’s theory supported the Law of Conservation of Mass.
18. D – He could not explain isotopes (atoms of same element with different masses).
19. B – Atoms rearranged but not changed → Law of Conservation of Mass.
20. D – J.J. Thomson discovered electrons, modifying Dalton’s idea of indivisible atoms.
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