Question

Following statements are given:
(A) The average kinetic energy of a gas molecule decreases when the temperature is reduced.
(B) The average kinetic energy of a gas molecule increases with increase in pressure at constant temperature.
(C) The average kinetic energy of a gas molecule decreases with increase in volume.
(D) Pressure of a gas increases with increase in temperature at constant pressure.
(E) The volume of gas decreases with increase in temperature.
Choose the correct answer from the options given below:

• A. (A) & (D) only
• B. (A), (B) & (D) only
• C. (B) & (D) only
• D. (A), (B) & (E) only

Answer 1

The Correct Option is A

Let's analyze each statement given in the question to determine which ones are correct:

1. Statement A: The average kinetic energy of a gas molecule decreases when the temperature is reduced.
   According to the kinetic theory of gases, the average kinetic energy of gas molecules is directly proportional to the absolute temperature. Therefore, if the temperature decreases, the average kinetic energy also decreases. This statement is true.
2. Statement B: The average kinetic energy of a gas molecule increases with increase in pressure at constant temperature.
   At constant temperature, the average kinetic energy of gas molecules remains constant, regardless of changes in pressure. Thus, this statement is false.
3. Statement C: The average kinetic energy of a gas molecule decreases with increase in volume.
   The average kinetic energy of gas molecules is dependent on temperature, not directly on volume. Therefore, this statement is false.
4. Statement D: Pressure of a gas increases with increase in temperature at constant pressure.
   This statement is intrinsically incorrect as it mentions pressure increases at constant pressure, which is contradictory in itself. However, assuming a logical interpretation: when the temperature of a gas increases at constant volume, the pressure increases, according to Gay-Lussac's law. This modified statement interpretation can be considered true.
5. Statement E: The volume of gas decreases with increase in temperature.
   According to Charles's Law, the volume of a gas increases with an increase in temperature, at constant pressure. This statement is false.

Considering the analysis above, the correct statements are (A) and interpreted (D).

Therefore, the correct answer is: (A) & (D) only