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Quiz Chapter 4: Heat

10 questions · Form 4 Physics Bab 4: Heat

Question 1 of 10Score: 0

Which graph correctly represents Boyle's Law for an ideal gas at constant temperature?

Full Question List & Answer Key

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

1. Which graph correctly represents Boyle's Law for an ideal gas at constant temperature?

  1. A straight line with positive slope when plotting P against V
  2. A straight line passing through origin when plotting P against 1V
  3. A horizontal straight line when plotting P against T
  4. A curved line with increasing slope when plotting P against 1V
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Answer: B

Since P ∝ 1V, a graph of P versus 1V yields a straight line passing through the origin.

2. According to the kinetic theory of gases, what happens to gas molecules when the temperature of the gas increases?

  1. Their average kinetic energy and average velocity increase
  2. The size of individual molecules expands
  3. The mass of gas molecules increases
  4. The frequency of molecular collisions with container walls decreases
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Answer: A

Temperature is a measure of the average kinetic energy of molecules. Increasing temperature speeds up molecular motion.

3. Why does the temperature of ice remain constant at 0°C while it is melting?

  1. No heat is being absorbed by the ice
  2. Heat absorbed is used to break intermolecular bonds rather than increase kinetic energy
  3. The ice releases heat into the environment at the same rate
  4. Latent heat reduces the kinetic energy of water molecules
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Answer: B

During a phase change, heat absorbed (latent heat) is used to overcome intermolecular forces of attraction. Average kinetic energy does not increase, keeping temperature constant.

4. Why is water used as a coolant agent in car engine radiators?

  1. Water has a low specific latent heat of fusion
  2. Water expands rapidly when heated
  3. Water has a very high specific heat capacity
  4. Water boils at low temperatures
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Answer: C

Water's high specific heat capacity (4200 J kg-1 °C-1 allows it to absorb a large amount of heat energy from the engine with only a small rise in temperature.

5. What condition must be fulfilled for two objects in thermal contact to achieve thermal equilibrium?

  1. They must have the same total heat energy content
  2. The net rate of heat transfer between them becomes zero
  3. They must have the same specific heat capacity
  4. Heat stops flowing between them entirely
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Answer: B

At thermal equilibrium, heat still transfers in both directions, but the net rate of heat transfer is zero because both objects are at the same temperature.

6. A fixed mass of gas in a rigid container has a pressure of 1.2 × 105 Pa at 27°C. What will its pressure be at 127°C?

  1. 1.6 × 105 Pa
  2. 5.64 × 105 Pa
  3. 1.2 × 105 Pa
  4. 2.4 × 105 Pa
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Answer: A

Convert temperatures to Kelvin: T1 = 27 + 273 = 300 K; T2 = 127 + 273 = 400 K. P1 / T1 = P2 / T2 => 1.2 × 105300 = P2 / 400 => P2 = 1.6 × 105 Pa.

7. What variable is kept constant in Gay-Lussac's Law?

  1. Pressure
  2. Temperature
  3. Volume
  4. Mass and Volume
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Answer: D

Gay-Lussac's Law investigates the relationship between pressure and temperature for a fixed mass of gas at constant volume.

8. A trapped gas in a cylinder has a volume of 0.04 m³ at a pressure of 100 kPa. If the gas is compressed at constant temperature to a volume of 0.01 m³, what is the new pressure?

  1. 25 kPa
  2. 200 kPa
  3. 400 kPa
  4. 500 kPa
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Answer: C

P1 V1 = P2 V2 => 100 × 0.04 = P2 × 0.01 => P2 = 40.01 = 400 kPa.

9. An electric heater rated at 500 W takes 4 minutes to melt 0.5 kg of ice at 0°C. Calculate the specific latent heat of fusion of ice.

  1. 2.4 × 105 J kg-1
  2. 1.2 × 105 J kg-1
  3. 4.8 × 105 J kg-1
  4. 6.0 × 104 J kg-1
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Answer: A

Q = P t = 500 × (4 × 60) = 120 000 J. Q = m l_f => l_f = 120 0000.5 = 240 000 J kg-1 = 2.4 × 105 J kg-1.

10. Which law states that for a fixed mass of gas at constant temperature, pressure is inversely proportional to volume?

  1. Gay-Lussac's Law
  2. Charles's Law
  3. Boyle's Law
  4. Newton's Law
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Answer: C

Boyle's Law describes the pressure-volume relationship at constant temperature: P ∝ 1V (P1 V1 = P2 V2).

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