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Mock Test 2

  • Time yourself: 20 minutes
  • No checking answers until finished
  • Focus on reasoning, not memorization

SECTION 1: MCQ

Question 1

Which element has the highest ionization energy?

  1. Na
  2. Mg
  3. Al
  4. Cl
Show answer

Correct answer: D

Why: Ionization energy increases across a period (left → right).

Common mistake: Thinking larger atoms have higher ionization energy.

Fix it: Smaller atom = harder to remove electron

Question 2

Which molecule has trigonal planar geometry?

  1. CH₄
  2. NH₃
  3. BF₃
  4. H₂O
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Correct answer: C

Why: BF₃ has 3 bonding pairs and no lone pairs → trigonal planar.

Fix it: 3 regions = trigonal planar

Question 3

Which has strongest intermolecular forces?

  1. CO₂
  2. CH₄
  3. NH₃
  4. H₂
Show answer

Correct answer: C

Why: NH₃ forms hydrogen bonds.

Fix it: H–N, H–O, H–F → hydrogen bonding

Question 4

For the reaction at equilibrium:
If Q > K, the reaction will:

  1. shift right
  2. shift left
  3. stay same
  4. stop
Show answer

Correct answer: B

Why: Too many products → system shifts left.

Fix it: Q > K → go backward

Question 5

Which change increases reaction rate?

  1. lower temperature
  2. add catalyst
  3. decrease concentration
  4. remove reactants
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Correct answer: B

Why: Catalyst lowers activation energy.

Fix it: Catalyst = faster reaction

Question 6

What is the pH of 1×10⁻⁵ M HCl?

  1. 3
  2. 4
  3. 5
  4. 6
Show answer

Correct answer: C

Why: pH = -log(10⁻⁵) = 5

Fix it: Exponent = pH

Question 7

Which process is endothermic?

  1. freezing
  2. condensation
  3. evaporation
  4. deposition
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Correct answer: C

Why: Evaporation absorbs heat.

Fix it: Liquid → gas = endothermic

Question 8

Increasing pressure shifts equilibrium toward:

  1. more moles gas
  2. fewer moles gas
  3. liquids
  4. solids
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Correct answer: B

Why: System reduces pressure by decreasing gas moles.

Fix it: High pressure → fewer moles

Question 9

  • Which species is oxidized?
  • Zn → Zn²⁺ + 2e⁻
  1. Zn
  2. Zn²⁺
  3. e⁻
  4. none
Show answer

Correct answer: A

Why: Oxidation = loss of electrons.

Fix it: LEO (Lose Electrons = Oxidation)

Question 10

Which solution is most basic?

  1. pH 3
  2. pH 5
  3. pH 7
  4. pH 12
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Correct answer: D

Why: Higher pH = more basic.

Fix it: pH ↑ → basic ↑

SECTION 2: FRQ

FRQ 1

Explain how a catalyst affects a reaction and why it does not change equilibrium position.

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Key points

  • lowers activation energy
  • speeds forward & reverse
  • does not change K

Sample answer: A catalyst lowers activation energy, increasing the rate of both forward and reverse reactions equally. It does not change the equilibrium constant, so equilibrium position remains unchanged.

FRQ 2

Explain how concentration changes affect equilibrium.

Show answer

Key points

  • system shifts to oppose change
  • Le Châtelier principle
  • restore equilibrium

Sample answer: When concentration changes, the system shifts to counteract the change. Increasing reactants shifts equilibrium toward products, while decreasing reactants shifts it toward reactants.