CSCA CHEM PREP

CSCA Chemistry Practice Exam (48 Questions with Answers & Explanations)

CSCA Chemistry Hard Mode Practice

Each question includes the correct answer and explanation to help you revise effectively.

Questions with Answers & Explanations

1. What is the molar mass of H₂SO₄?
A) 96 B) 98 C) 100 D) 102
Answer: B (98)
H=1×2, S=32, O=16×4 → 2+32+64 = 98 g/mol.
2. Which particle has no charge?
A) Proton B) Electron C) Neutron D) Ion
Answer: C
Neutrons are neutral; protons are +, electrons are -.
3. The pH of a strong acid is:
A) 7 B) >7 C) <7 D) 14
Answer: C
Strong acids have very low pH values below 7.
4. Which gas relights a glowing splint?
A) H₂ B) O₂ C) CO₂ D) N₂
Answer: B
Oxygen supports combustion, so it relights a glowing splint.
5. Avogadro’s number is:
A) 6.02×10²³ B) 3.01×10²³ C) 9.81 D) 1.66×10⁻²⁷
Answer: A
It represents number of particles in 1 mole.
6. Which bond involves sharing electrons?
A) Ionic B) Covalent C) Metallic D) Hydrogen
Answer: B
Covalent bonds share electron pairs between atoms.
7. Most reactive Group 1 element:
A) Li B) Na C) K D) Cs
Answer: D
Reactivity increases down the group.
8. Formula of ammonia:
A) NH₂ B) NH₃ C) NO₂ D) N₂H₄
Answer: B
Ammonia contains 1 nitrogen and 3 hydrogens.
9. Separation by boiling point:
A) Filtration B) Distillation C) Chromatography D) Decanting
Answer: B
Distillation separates based on different boiling points.
10. Oxidation is:
A) Gain e⁻ B) Loss e⁻ C) Gain n D) Loss p
Answer: B
Oxidation = loss of electrons (OIL RIG rule).
11. Atomic number equals protons.
Answer: A
Atomic number defines number of protons.
12. NaCl bonding:
Answer: C (Ionic)
Metal + non-metal = ionic bond.
13. Water is neutral.
Answer: C
Pure water has pH 7.
14. Acid + metal produces hydrogen.
Answer: D
Hydrogen gas is released.
15. Catalyst increases rate.
Answer: B
It lowers activation energy.
16. Unit of concentration:
Answer: A
mol/dm³ is standard.
17. Electron charge:
Answer: B
Electrons are negatively charged.
18. Noble gases are inert.
Answer: B
Full outer shells make them stable.
19. CO₂ is acidic oxide.
Answer: C
It forms carbonic acid in water.
20. Oxygen atomic number:
Answer: C (8)
Oxygen has 8 protons.
21. Endothermic absorbs heat.
Answer: B
Energy is taken in.
22. Acid turns blue litmus red.
Answer: A
Classic acid test.
23. Methane = CH₄.
Answer: C
Simplest hydrocarbon.
24. Strong base NaOH.
Answer: A
Fully dissociates in water.
25. Mass number = p+n.
Answer: A
Total nucleons.
26. Electrolysis uses electricity.
Answer: B
Drives chemical change.
27. CO₂ test = limewater milky.
Answer: C
Forms CaCO₃ precipitate.
28. Reactivity increases down Group 1.
Answer: C
Outer electron easier to lose.
29. Steel is alloy.
Answer: B
Mixture of iron + carbon.
30. Boiling is physical change.
Answer: B
No new substance formed.
31. Empirical formula = simplest ratio.
Answer: B
Reduced form of molecular formula.
32. pH 14 = strong base.
Answer: D
Highly alkaline.
33. Catalyst speeds reaction.
Answer: A
Not consumed.
34. Haber process makes ammonia.
Answer: B
N₂ + H₂ → NH₃.
35. Oxygen oxidation state = -2.
Answer: A
Common oxidation number.
36. Electrolytes conduct via ions.
Answer: B
Ions carry charge in solution.
37. Alkali metals form +1 ions.
Answer: A
Lose one electron.
38. Metallic bonding in metals.
Answer: B
Sea of delocalized electrons.
39. pH 7 is green.
Answer: C
Neutral solution color.
40. Reduction = gain electrons.
Answer: A
RIG rule.
41. Solvent = larger amount.
Answer: B
Dissolves solute.
42. Exothermic releases heat.
Answer: B
Energy flows out.
43. Halogens = reactive non-metals.
Answer: C
Group 7 elements.
44. Relative atomic mass = weighted average.
Answer: B
Accounts for isotopes.
45. pH 1 = strong acid.
Answer: B
Highly acidic.
46. Rusting needs oxygen + water.
Answer: A
Both required.
47. Ionic compounds have high melting points.
Answer: D
Strong electrostatic forces.
48. Catalyst speeds reaction without being used.
Answer: C
Remains unchanged after reaction.

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