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Quiz Chapter 7: Rate of Reaction

10 questions · Form 4 Chemistry Bab 7: Rate of Reaction

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. What happens to the particles when the temperature of a reaction mixture increases?

  1. Activation energy decreases significantly
  2. Their average kinetic energy increases, leading to more frequent effective collisions
  3. The overall enthalpy change of the reaction becomes positive
  4. The orientation of particle collisions is no longer required
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Answer: B

Higher temperature increases kinetic energy, causing particles to move faster and collide more frequently with energy ≥ Ea.

2. Why does increasing pressure increase the rate of reaction for gaseous reactants?

  1. It lowers the activation energy barrier
  2. It increases the temperature of the gas mixture
  3. It increases the number of gas particles per unit volume
  4. It changes the chemical nature of the gases
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Answer: C

Compressing gas into a smaller volume increases particle density per unit volume, raising collision frequency.

3. Which reaction can have its rate determined by observing the formation of a yellow precipitate?

  1. Zinc and hydrochloric acid
  2. Sodium thiosulfate and sulfuric acid
  3. Calcium carbonate and nitric acid
  4. Copper(II) sulfate and sodium hydroxide
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Answer: B

The reaction between sodium thiosulfate and sulfuric acid produces sulfur, which forms a insoluble yellow precipitate.

4. If 50 cm³ of carbon dioxide gas is collected in 20 seconds, what is the average rate of reaction?

  1. 2.5 cm³/s
  2. 0.4 cm³/s
  3. 1000 cm³/s
  4. 10.0 cm³/s
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Answer: A

Average rate = Total volume / Total time = 50 cm³ / 20 s = 2.5 cm³/s.

5. Which condition describes the optimum environment for Stage 2 of the Contact Process?

  1. 450°C, 1 atm, Vanadium(V) oxide catalyst
  2. 200°C, 200 atm, Iron catalyst
  3. 500°C, 200 atm, Nickel catalyst
  4. 100°C, 10 atm, Platinum catalyst
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Answer: A

The Contact Process uses 450°C, 1 atm pressure, and a Vanadium(V) oxide (V2O5) catalyst to convert SO2 to SO3.

6. What role does a catalyst play in speeding up a chemical reaction?

  1. It increases the average kinetic energy of reactant particles
  2. It increases the frequency of total collisions between reactants
  3. It lowers the activation energy by providing an alternative reaction pathway
  4. It increases the enthalpy change of the reaction
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Answer: C

A catalyst provides an alternative pathway with lower activation energy, increasing the number of effective collisions.

7. Which catalyst is used in the decomposition of hydrogen peroxide to produce oxygen gas in laboratory demonstrations?

  1. Manganese(IV) oxide
  2. Iron filings
  3. Phosphoric acid
  4. Aluminium oxide
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Answer: A

Manganese(IV) oxide (MnO2) acts as a catalyst to speed up the decomposition of H2O2 into H2O and O2 gas.

8. Which curve in a rate experiment graph represents the fastest reaction rate?

  1. The curve with the steepest initial gradient
  2. The curve that takes the longest time to reach a flat line
  3. The curve with the lowest final volume
  4. The linear straight line along the x-axis
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Answer: A

The gradient of the curve represents the rate of reaction; a steeper initial curve means a higher initial reaction rate.

9. What happens to the mass of a catalyst at the end of a chemical reaction?

  1. It doubles
  2. It decreases by half
  3. It drops to zero
  4. It remains unchanged
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Answer: D

A catalyst increases reaction speed without undergoing any permanent chemical or quantitative mass change.

10. Which practical application utilizes the effect of total surface area on reaction rate?

  1. Cooking food in a pressure cooker
  2. Cutting meat or vegetables into smaller pieces before cooking
  3. Adding yeast when baking bread
  4. Storing milk inside an icebox
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Answer: B

Cutting food into smaller pieces increases total exposed surface area, allowing heat to transfer faster and cook food quicker.

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