1. Who proposed that matter is made of indivisible particles called Parmanu?
A. Dalton
B. Democritus
C. Maharishi Kanad
D. Lavoisier
Answer: C
2. Who coined the term “atom” (meaning indivisible)?
A. Leucippus
B. Dalton
C. Democritus
D. Proust
Answer: C
3. Law of Conservation of Mass was given by:
A. Proust
B. Lavoisier
C. Dalton
D. Rutherford
Answer: B
4. Law of Constant Proportion was given by:
A. Dalton
B. Avogadro
C. Proust
D. Lavoisier
Answer: C
5. According to the Law of Conservation of Mass:
A. Mass increases in a reaction
B. Mass decreases in a reaction
C. Mass remains unchanged
D. Mass is created
Answer: C
6. In water, hydrogen and oxygen are combined in which mass ratio?
A. 1:16
B. 1:2
C. 1:8
D. 2:8
Answer: C
7. According to Dalton’s theory, atoms are:
A. Always divisible
B. Created in reactions
C. Indivisible
D. Invisible but divisible
Answer: C
8. Atomic radius is measured in:
A. cm
B. m
C. nanometres
D. millimetres
Answer: C
9. Symbol of Sodium is:
A. So
B. S
C. Na
D. Sn
Answer: C
10. Which of the following is a diatomic molecule?
A. Helium
B. Argon
C. Nitrogen
D. Sulphur
Answer: C
11. Atomicity of phosphorus (P₄) is:
A. 1
B. 2
C. 3
D. 4
Answer: D
12. Ozone (O₃) is:
A. Monoatomic
B. Diatomic
C. Triatomic
D. Polyatomic
Answer: C
13. The combining capacity of an element is called:
A. Mass
B. Valency
C. Atomicity
D. Reactivity
Answer: B
14. Which of the following is a polyatomic ion?
A. Cl⁻
B. O²⁻
C. PO₄³⁻
D. Na⁺
Answer: C
15. The chemical formula of calcium hydroxide is:
A. CaOH₂
B. Ca(OH)₂
C. CaO₂H
D. Ca(OH)
Answer: B
16. Molecular mass of CO₂ is:
A. 28 u
B. 32 u
C. 40 u
D. 44 u
Answer: D
17. Formula unit mass is used for:
A. Molecular compounds
B. Ionic compounds
C. Metals only
D. Non-metals only
Answer: B
18. Sodium chloride consists of:
A. Na and Cl atoms
B. Na⁺ and Cl⁻ ions
C. Na²⁺ and Cl²⁻ ions
D. Na³⁺ and Cl³⁻ ions
Answer: B
19. Formula of aluminium oxide is:
A. AlO
B. Al₂O₃
C. AlO₂
D. Al₃O₂
Answer: B
20. The atomic mass unit is based on:
A. Oxygen-16
B. Carbon-12
C. Nitrogen-14
D. Hydrogen-1
Answer: B
21. Which one has monoatomic molecules?
A. Oxygen
B. Chlorine
C. Argon
D. Nitrogen
Answer: C
22. Mass of 1 atom of carbon-12 is divided into how many parts to define 1u?
A. 6
B. 10
C. 12
D. 16
Answer: C
23. What is the valency of phosphate ion (PO₄³⁻)?
A. 1
B. 2
C. 3
D. 4
Answer: C
24. Which of the following is a binary compound?
A. CaCO₃
B. NaNO₃
C. NaCl
D. H₂SO₄
Answer: C
25. The atomic mass of chlorine is:
A. 17
B. 32
C. 35.5
D. 40
Answer: C
26. Molecular mass of H₂O is:
A. 10 u
B. 12 u
C. 18 u
D. 20 u
Answer: C
27. Identify the cation:
A. SO₄²⁻
B. Cl⁻
C. NH₄⁺
D. CO₃²⁻
Answer: C
28. Formula of magnesium chloride is:
A. MgCl
B. MgCl₂
C. Mg₂Cl
D. Mg₂Cl₃
Answer: B
29. The molecule capable of independent existence is called:
A. Ion
B. Atom
C. Element
D. Molecule
Answer: D
30. Calculate the formula unit mass of NaCl.
A. 23 u
B. 35.5 u
C. 40 u
D. 58.5 u
Answer: D
📘 Fill in the Blanks (5 Questions)
1. The smallest particle of an element that participates in a chemical reaction is called an ________.
Answer: Atom
2. The law which states that mass can neither be created nor destroyed is known as the law of ____________________.
Answer: Conservation of Mass
3. Water always contains hydrogen and oxygen in the mass ratio of ________.
Answer: 1:8
4. The combining capacity of an element is called its ____________.
Answer: Valency
5. A negatively charged ion is called an ____________.
Answer: Anion
📘 True/False (5 Questions)
6. Dalton stated that atoms of different elements have different masses and chemical properties.
Answer: True
7. Atoms can be seen easily with the naked eye.
Answer: False
8. In the formula Ca(OH)₂, there are two hydroxyl groups.
Answer: True
9. Ozone (O₃) is a diatomic molecule.
Answer: False (It is triatomic)
10. Sodium chloride contains Na⁺ and Cl⁻ ions.
Answer: True