Exams › JEE Main › Physics
The temperature of an open room of volume 30 m³ increases from 17°C to 27°C due to the sunshine. The atmospheric pressure in the room remains 1 × 10⁵ Pa. In n_i and n_f are the number of molecules in the room before and after heating, then n_f - n_i =
- -1.61 × 10²³
- 1.38 × 10²³
- 2.5 × 10²⁵
- -2.5 × 10²⁵
Correct answer: -2.5 × 10²⁵
Solution
The correct option is -2.5 × 10²⁵ because as the temperature increases, the air expands, causing a decrease in the number of molecules in the room if the volume remains constant and the pressure is held steady. This results in a negative change in the number of molecules, indicating a loss.
Related JEE Main Physics questions
- An ideal gas is enclosed in a thermally insulated sealed container. During an adiabatic expansion, the mean interval between successive molecular collisions varies with the volume V as V^q. What is the value of q in terms of γ = Cp/Cv?
- At 300 K, the root mean square speed of hydrogen molecules is 1930 m/s. What will be the r.m.s. speed of oxygen molecules at 1200 K?
- A gaseous mixture contains 2 moles of oxygen and 4 moles of argon at temperature T. If vibrational degrees of freedom are ignored, what is the total internal energy of the mixture?
- If all intermolecular attractions were removed, what volume would be occupied by the molecules present in 4.5 g of water at standard temperature and pressure?
- An ideal gas sample has volume V, pressure P, and absolute temperature T. If the mass of one molecule is m, which expression gives the density of the gas?
- A vessel at temperature T contains N molecules of gas A, each having mass m, and 2N molecules of gas B, each having mass 2m. If the mean square speed of molecules of gas B is V2 and that of gas A is V1, then the ratio V1/V2 equals
⚔️ Practice JEE Main Physics free + battle 1v1 →