arrow_backBack to Study Resources

Quiz Chapter 7: Rate of Reaction

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

Question 1 of 10Score: 0

In a curve showing gas volume against time, what does a horizontal flat line indicate?

Full Question List & Answer Key

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

1. In a curve showing gas volume against time, what does a horizontal flat line indicate?

  1. The rate of reaction is at its maximum
  2. The reaction has completed because at least one reactant is fully used up
  3. The catalyst has been exhausted
  4. The activation energy has increased to infinity
Show answer

Answer: B

A horizontal flat gradient indicates that gas production has ceased because the limiting reactant is completely consumed.

2. According to collision theory, what two criteria are required for an effective collision?

  1. Low temperature and high pressure
  2. Correct collision orientation and energy equal to or greater than activation energy
  3. Presence of a catalyst and large surface area
  4. High concentration and small volume
Show answer

Answer: B

For a collision to be effective, particles must collide with correct orientation and sufficient energy (E >= Ea).

3. 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
Show answer

Answer: A

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

4. What is the catalyst used in the Haber Process for manufacturing ammonia?

  1. Platinum
  2. Iron
  3. Vanadium(V) oxide
  4. Manganese(IV) oxide
Show answer

Answer: B

Finely divided iron (Fe) acts as the catalyst to speed up the synthesis of ammonia in the Haber Process.

5. 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
Show answer

Answer: B

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

6. 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
Show answer

Answer: D

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

7. 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
Show answer

Answer: B

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

8. What is activation energy (Ea)?

  1. The heat released during a chemical reaction
  2. The energy level of the final products
  3. The minimum energy reactant particles must possess to react
  4. The total kinetic energy of all system particles
Show answer

Answer: C

Activation energy is the minimum barrier energy required by colliding particles to break bonds and initiate a reaction.

9. Why do powdered marble chips (CaCO3) react faster with hydrochloric acid than marble lumps of the same mass?

  1. Powdered marble has lower activation energy
  2. Powdered marble increases the kinetic energy of acid molecules
  3. Powdered marble provides a larger total surface area exposed to collision
  4. Powdered marble increases the concentration of the acid solution
Show answer

Answer: C

Smaller particle size provides a larger total surface area exposed to reactant collisions, increasing collision frequency.

10. 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
Show answer

Answer: A

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

Sponsored