- If the absolute temperature of a gas is decreased, the average kinetic energy of its molecules:
A) Increases.
B) Decreases.
C) Remains the same.
D) Becomes negative.
Answer: B) Decreases.
Explanation: The average kinetic energy of gas molecules is directly proportional to temperature; thus, lowering the temperature decreases the kinetic energy.
- Which gas is often used as an example of an ideal gas?
A) Oxygen (O2)
B) Carbon Dioxide (CO2)
C) Neon (Ne)
D) Ammonia (NH3)
Answer: C) Neon (Ne)
Explanation: Noble gases like Neon exhibit behavior closest to that of an ideal gas due to minimal intermolecular forces and small size.
- The term “absolute zero” refers to:
A) 0 degrees Celsius.
B) 273.15 degrees Celsius.
C) 0 Kelvin.
D) The freezing point of water.
Answer: C) 0 Kelvin.
Explanation: Absolute zero is defined as 0 Kelvin, which corresponds to the theoretical point where molecular motion ceases entirely.
- The concept of pressure in gases arises from:
A) The weight of gas molecules.
B) The collision of gas molecules with the walls of their container.
C) The volume occupied by the gas.
D) The temperature of the gas.
Answer: B) The collision of gas molecules with the walls of their container.
Explanation: Pressure is created by the force exerted when gas molecules collide with the walls of their container.
- Which of the following is a characteristic of an ideal gas?
A) High density.
B) Strong intermolecular forces.
C) Elastic collisions.
D) Significant volume.
Answer: C) Elastic collisions.
Explanation: Ideal gases are characterized by perfectly elastic collisions between molecules, meaning kinetic energy is conserved.
- The speed of sound in a gas is influenced by:
A) Temperature.
B) Molar mass.
C) Pressure.
D) Both A and B.
Answer: D) Both A and B.
Explanation: The speed of sound in a gas is affected by both the temperature and the molar mass of the gas, with higher temperatures and lower molar masses resulting in faster sound speeds.
- If a gas expands into a vacuum, the process is known as:
A) Isothermal expansion.
B) Isobaric expansion.
C) Free expansion.
D) Adiabatic expansion.
Answer: C) Free expansion.
Explanation: Free expansion occurs when a gas expands into a vacuum without doing work and without heat exchange.
- In a gas, the average distance between molecules increases with:
A) Increasing temperature.
B) Decreasing pressure.
C) Increasing volume.
D) All of the above.
Answer: D) All of the above.
Explanation: As temperature increases, pressure decreases, or volume increases, the average distance between gas molecules increases.
- If the volume of a gas is tripled at constant temperature, what happens to the pressure?
A) Pressure increases by a factor of three.
B) Pressure decreases to one-third.
C) Pressure remains constant.
D) Pressure doubles.
Answer: B) Pressure decreases to one-third.
Explanation: According to Boyle’s Law, if the volume increases, the pressure decreases proportionally.
- Which of the following is true regarding the ideal gas law?
A) It applies only at very low pressures.
B) It is valid for all gases at all conditions.
C) It provides an approximation for real gases under many conditions.
D) It applies only to monoatomic gases.
Answer: C) It provides an approximation for real gases under many conditions.
Explanation: The ideal gas law approximates the behavior of real gases under many conditions but fails at very high pressures and low temperatures.
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