MCQs
1. The law stating that mass can neither be created nor destroyed is:
A. Law of Multiple Proportions
B. Law of Conservation of Mass
C. Avogadro’s Law
D. Boyle’s Law
Answer: B
2. The scientist who proposed the Law of Conservation of Mass was:
A. Dalton
B. Rutherford
C. Antoine Lavoisier
D. Proust
Answer: C
3. During a physical change, total mass:
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: C
4. In the reaction between vinegar and baking soda, the gas produced is:
A. Oxygen
B. Hydrogen
C. Carbon dioxide
D. Nitrogen
Answer: C
5. The Law of Constant Proportions was proposed by:
A. Dalton
B. Proust
C. Chadwick
D. Thomson
Answer: B
6. According to the Law of Constant Proportions, elements combine:
A. In any ratio
B. In fixed ratio by mass
C. In equal volumes
D. In equal number of atoms only
Answer: B
7. Water always contains hydrogen and oxygen in the mass ratio:
A. 1 : 2
B. 2 : 1
C. 1 : 8
D. 8 : 1
Answer: C
8. Dalton proposed that matter is made up of tiny particles called:
A. Molecules
B. Electrons
C. Atoms
D. Ions
Answer: C
9. According to Dalton, atoms are:
A. Divisible
B. Destroyed in reactions
C. Indivisible
D. Made of ions only
Answer: C
10. Atoms combine in:
A. Random ratios
B. Fractional ratios only
C. Simple whole number ratios
D. Equal masses only
Answer: C
11. A molecule is:
A. A charged particle
B. A neutral group of atoms
C. Only a single atom
D. A proton
Answer: B
12. The force holding atoms together is called:
A. Gravitational force
B. Magnetic force
C. Chemical bond
D. Frictional force
Answer: C
13. Covalent bond is formed by:
A. Transfer of electrons
B. Sharing of electrons
C. Transfer of protons
D. Sharing of neutrons
Answer: B
14. Hydrogen molecule contains:
A. One hydrogen atom
B. Two hydrogen atoms
C. Three hydrogen atoms
D. Four hydrogen atoms
Answer: B
15. The formula of hydrogen molecule is:
A. H
B. H₂
C. H₂O
D. HCl
Answer: B
16. In oxygen molecule, atoms are joined by:
A. Single bond
B. Double bond
C. Triple bond
D. Ionic bond
Answer: B
17. Chlorine molecule is represented as:
A. Cl
B. Cl₂
C. Cl₃
D. Cl⁻
Answer: B
18. The bond in HCl is:
A. Ionic bond
B. Metallic bond
C. Covalent bond
D. Hydrogen bond
Answer: C
19. Water molecule contains:
A. One H and one O atom
B. Two H and one O atom
C. Two O and one H atom
D. Three H atoms
Answer: B
20. A sodium atom forms Na⁺ by:
A. Gaining one electron
B. Sharing one electron
C. Losing one electron
D. Gaining two electrons
Answer: C
21. Chlorine atom forms Cl⁻ by:
A. Losing one electron
B. Gaining one electron
C. Sharing two electrons
D. Losing two electrons
Answer: B
22. Electrostatic attraction between oppositely charged ions forms:
A. Covalent bond
B. Metallic bond
C. Ionic bond
D. Hydrogen bond
Answer: C
23. Sodium chloride is an example of:
A. Covalent compound
B. Ionic compound
C. Molecular element
D. Noble gas
Answer: B
24. Positively charged ions are called:
A. Anions
B. Molecules
C. Cations
D. Isotopes
Answer: C
25. Negatively charged ions are called:
A. Cations
B. Anions
C. Atoms
D. Radicals
Answer: B
26. Which ion is polyatomic?
A. Cl⁻
B. O²⁻
C. SO₄²⁻
D. Na⁺
Answer: C
27. Formula of calcium chloride is:
A. CaCl
B. Ca₂Cl
C. CaCl₂
D. Ca₂Cl₂
Answer: C
28. Formula of aluminium oxide is:
A. AlO
B. Al₂O₃
C. Al₃O₂
D. AlO₂
Answer: B
29. Formula of magnesium hydroxide is:
A. MgOH
B. Mg(OH)₂
C. Mg₂OH
D. MgO₂H₂
Answer: B
30. Brackets are used in chemical formulae when:
A. One atom is present
B. Polyatomic ions repeat
C. Ionic bond absent
D. Molecule is neutral
Answer: B
Assertion–Reason MCQs
31.
Assertion (A): Mass remains constant during a chemical reaction.
Reason (R): Matter can neither be created nor destroyed.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
32.
Assertion (A): Water from all sources has same composition.
Reason (R): Water follows the Law of Constant Proportions.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
33.
Assertion (A): Sodium chloride conducts electricity in aqueous solution.
Reason (R): It produces free ions in water.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
34.
Assertion (A): Covalent compounds generally have low melting points.
Reason (R): Intermolecular forces in covalent compounds are weak.
A. Both A and R are true, and R explains A
B. Both A and R are true, but R does not explain A
C. A is true but R is false
D. A is false but R is true
Answer: A
Case-Based MCQs
Case Study 1
A student mixed sodium sulfate solution with barium chloride solution and observed formation of a white precipitate.
35. The white precipitate formed is:
A. Sodium chloride
B. Barium sulfate
C. Sulfur dioxide
D. Barium oxide
Answer: B
36. During the reaction, total mass:
A. Increases
B. Decreases
C. Remains constant
D. Becomes zero
Answer: C
37. This experiment verifies:
A. Boyle’s law
B. Dalton’s law
C. Law of Conservation of Mass
D. Ohm’s law
Answer: C
Case Study 2
An oxygen atom combines with another oxygen atom by sharing electrons.
38. The bond formed is:
A. Ionic bond
B. Double covalent bond
C. Triple bond
D. Metallic bond
Answer: B
39. Oxygen molecule is represented as:
A. O
B. O₂
C. O₃
D. O⁻
Answer: B
Competency-Based MCQs
40. Which compound will conduct electricity in water?
A. Sugar
B. Camphor
C. Sodium chloride
D. Naphthalene
Answer: C
41. Which compound is most likely covalent?
A. NaCl
B. MgO
C. CO₂
D. CaCl₂
Answer: C
42. Molecular mass of water is:
H_2O=(1\times2)+(16\times1)=18,u
A. 16 u
B. 17 u
C. 18 u
D. 20 u
Answer: C
43. Formula unit mass of Na₂O is:
Na_2O=(23\times2)+16=62,u
A. 46 u
B. 62 u
C. 78 u
D. 39 u
Answer: B
44. Formula of calcium carbonate is:
A. CaCO₂
B. Ca₂CO₃
C. CaCO₃
D. Ca(CO₃)₂
Answer: C
45. Which compound contains a triple bond?
A. O₂
B. H₂
C. N₂
D. Cl₂
Answer: C
46. Which pair forms an ionic compound?
A. Hydrogen and chlorine
B. Sodium and chlorine
C. Oxygen and hydrogen
D. Nitrogen and hydrogen
Answer: B
47. Which property is typical of ionic compounds?
A. Low melting point
B. Insoluble in water
C. Conduct electricity in solution
D. Do not form ions
Answer: C
48. Which compound contains polyatomic ion?
A. NaCl
B. MgO
C. CaCO₃
D. H₂
Answer: C
49. Formula of aluminium sulfate is:
A. AlSO₄
B. Al₂SO₄
C. Al₂(SO₄)₃
D. Al₃SO₄₂
Answer: C
50. Which statement BEST explains covalent bonding?
A. Atoms transfer protons
B. Atoms share electrons to become stable
C. Atoms lose neutrons
D. Atoms exchange nuclei
Answer: B
