NEET 2025 MCQ with Answer Explanation : “Gas Laws”.

Here below some basic MCQ’s about “Gas Laws” with answer which is well explained. Let’s check one by one.

1. Which of the following gas laws states that the volume of a gas is directly proportional to its temperature at constant pressure?
   A) Boyle’s Law
   B) Charles’s Law
   C) Avogadro’s Law
   D) Dalton’s Law

Answer: B) Charles’s Law

Explanation: Charles’s Law states that the volume of a gas increases with an increase in temperature when pressure is held constant. This relationship can be expressed as

V∝T (where V is volume and T is temperature in Kelvin).

2. What does Boyle’s Law state about the relationship between pressure and volume?
   A) Pressure is directly proportional to volume.
   B) Pressure is inversely proportional to volume.
   C) Pressure is equal to volume at constant temperature.
   D) Volume is constant regardless of pressure changes.

Answer: B) Pressure is inversely proportional to volume.

Explanation: Boyle’s Law states that at constant temperature, the pressure of a gas is inversely related to its volume. This means that if the volume increases, the pressure decreases and vice versa, which can be expressed as

PV=k (where k is a constant).

3. According to Avogadro’s Law, what is the relationship between the volume of a gas and the number of moles at constant temperature and pressure?
   A) Volume is directly proportional to the pressure.
   B) Volume is directly proportional to the number of moles.
   C) Volume is inversely proportional to the temperature.
   D) Volume remains constant regardless of the number of moles.

Answer: B) Volume is directly proportional to the number of moles.

Explanation: Avogadro’s Law states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules (or moles). Therefore, if the amount of gas increases, the volume also increases, provided temperature and pressure are constant.

4. Which of the following statements is true according to Dalton’s Law of Partial Pressures?
   A) The total pressure of a gas mixture is equal to the sum of the partial pressures of each gas.
   B) The total volume of a gas mixture is equal to the sum of the volumes of each gas.
   C) The pressure of a gas is directly related to its temperature.
   D) The partial pressure of a gas is equal to the total pressure divided by the number of gases.

Answer: A) The total pressure of a gas mixture is equal to the sum of the partial pressures of each gas.

5. In an ideal gas, what is the relationship between temperature and kinetic energy?
   A) Kinetic energy is directly proportional to the volume.
   B) Kinetic energy is directly proportional to the pressure.
   C) Kinetic energy is directly proportional to the temperature.
   D) Kinetic energy is independent of temperature.

Answer: C) Kinetic energy is directly proportional to the temperature.

6. If the temperature of a gas increases at constant volume, what happens to the pressure of the gas?
   A) It decreases.
   B) It remains constant.
   C) It increases.
   D) It becomes zero.

Answer: C) It increases.

Explanation: According to Gay-Lussac’s Law, the pressure of a gas increases as its temperature increases, provided the volume is held constant. This is because increasing temperature causes gas particles to move more rapidly, resulting in more collisions and higher pressure.

7. Which gas law can be represented by the equation PV=nRT?

A) Boyle’s Law
B) Charles’s Law
C) Ideal Gas Law
D) Avogadro’s Law

Answer: C) Ideal Gas Law

Explanation: The Ideal Gas Law combines several gas laws and relates pressure (P), volume (V), number of moles (n), the universal gas constant (R), and temperature (T). It provides a comprehensive description of the behavior of ideal gases.

8. What happens to the volume of a gas when it is compressed at constant temperature?
   A) It increases.
   B) It decreases.
   C) It remains constant.
   D) It doubles.

Answer: B) It decreases.

Explanation: According to Boyle’s Law, if the temperature remains constant, compressing a gas will reduce its volume because the gas molecules are forced closer together, resulting in an increase in pressure.

9. In which scenario is the behavior of real gases closest to that of an ideal gas?
   A) At high pressures and low temperatures.
   B) At low pressures and high temperatures.
   C) At low pressures and low temperatures.
   D) At high pressures and high temperatures.

Answer: B) At low pressures and high temperatures.

Explanation: Real gases behave more like ideal gases at low pressures and high temperatures because the intermolecular forces and the volume occupied by the gas particles become negligible under these conditions.

10. What is the effect of increasing the number of moles of gas in a rigid container at constant temperature?
    A) The pressure increases.
    B) The pressure decreases.
    C) The volume increases.
    D) The temperature increases.

Answer: A) The pressure increases.

Explanation: According to Avogadro’s Law, increasing the number of moles of gas in a fixed volume (rigid container) at constant temperature will increase the pressure due to more frequent collisions of gas particles with the container walls.