Daltons Atomic Theory - UNSOLVED PRACTICE SET
Chapter: Atoms | Topic: Daltons Atomic Theory
DALTONS ATOMIC THEORY - UNSOLVED PRACTICE SET
Topic: Daltons Atomic Theory
Multiple Choice Questions
Q1. According to Dalton's atomic theory, matter is made up of:
- Molecules which are divisible
- Atoms which are indivisible and indestructible
- Electrons and protons only
- A continuous fluid without any discrete particles
Q2. Dalton proposed that atoms of the same element are:
- Different in mass and size
- Identical in mass, size, and other properties
- Different in chemical properties
- Capable of being created or destroyed
Q3. Which of the following was NOT a postulate of Dalton's atomic theory?
- Atoms combine in simple whole number ratios to form compounds
- Atoms can be divided into smaller subatomic particles
- Atoms of different elements have different properties
- In a chemical reaction, atoms are neither created nor destroyed
Q4. Dalton's atomic theory successfully explained:
- The existence of isotopes
- The law of conservation of mass and the law of definite proportions
- The nuclear structure of the atom
- The wave nature of electrons
Q5. The limitation of Dalton's theory regarding isotopes is that it could not explain:
- Why atoms combine
- Why atoms of the same element can have different masses
- The law of multiple proportions
- The existence of compounds
Q6. Dalton's atomic theory was proposed in the year:
- 1708
- 1808
- 1908
- 1608
Short Answer Questions
Q7. State the main postulates of Dalton's atomic theory.
Q8. How did Dalton's atomic theory explain the law of conservation of mass?
Q9. What is the law of definite proportions? How did Dalton's theory account for it?
Q10. Name two successes and two limitations of Dalton's atomic theory.
Q11. Why did Dalton consider atoms to be indivisible? What discovery proved this assumption wrong?
Q12. How did Dalton's atomic theory lay the foundation for modern chemistry?
Long Answer Questions
Q13. State and explain the main postulates of Dalton's atomic theory. Discuss how this theory successfully explained the laws of chemical combination.
Q14. Explain the limitations of Dalton's atomic theory in light of modern discoveries. Discuss how the discovery of electrons, protons, neutrons, and isotopes contradicted various postulates of the theory.
Q15. Compare Dalton's atomic theory with the modern view of the atom. What aspects of Dalton's theory are still valid today, and what aspects have been modified or discarded?
Numerical & Application-based Problems
Q16. According to Dalton's atomic theory, hydrogen and oxygen combine to form water in a fixed ratio. In an experiment, 4 g of hydrogen reacts completely with 32 g of oxygen to form 36 g of water.
(a) Verify the law of conservation of mass using this data.
(b) Calculate the ratio of the masses of hydrogen and oxygen in water.
(c) If Dalton assumed that one atom of hydrogen combines with one atom of oxygen to form one atom of water, what would be the ratio of the masses of hydrogen and oxygen atoms?
(d) Explain why this simple assumption does not match the actual ratio, and how this led to the concept of atomic mass.
Q17. Two elements A and B form two different compounds. In the first compound, 10 g of A combines with 20 g of B. In the second compound, 15 g of A combines with 45 g of B.
(a) Calculate the mass of B that combines with a fixed mass of A in both compounds.
(b) Verify the law of multiple proportions using this data.
(c) Explain how Dalton's atomic theory accounts for this law.
Q18. In your school's chemistry lab, a student is studying the composition of different compounds to understand Dalton's atomic theory.
(a) She analyses carbon dioxide and finds that 12 g of carbon combines with 32 g of oxygen. She then analyses carbon monoxide and finds that 12 g of carbon combines with 16 g of oxygen. Show that these results illustrate the law of multiple proportions.
(b) The student then looks at data for two oxides of nitrogen: in N₂O, 28 g of nitrogen combines with 16 g of oxygen; in NO₂, 14 g of nitrogen combines with 32 g of oxygen. Verify the law of multiple proportions for these compounds.
(c) A classmate argues that since atoms are now known to be divisible, Dalton's entire theory is useless. Present a balanced argument explaining which parts of Dalton's theory remain valuable and which have been superseded by modern physics.
(d) In the context of modern atomic theory, explain why the concept of atoms as the smallest unit of chemical reactions is still valid, even though we now know about subatomic particles.