On the basis of kinetic theory of gases, the gas exerts pressure because its molecules:
| 1. | continuously lose their energy till it reaches wall. |
| 2. | are attracted by the walls of container. |
| 3. | continuously stick to the walls of container. |
| 4. | suffer change in momentum when impinge on the walls of container. |
The root mean square speed of molecules of a given mass of a gas at \(27^\circ \text{C}\) and \(1~\text{atm}\) is \(200~\text{m/s}\) The root mean square speed of molecules of the gas at \(127^\circ \text{C}\) and \(2~\text{atm}\) will be:
| 1. | \(\dfrac{200}{\sqrt{3}}~\text{m/s}\) | 2. | \(\dfrac{200}{\sqrt{5}}~\text{m/s}\) |
| 3. | \(\dfrac{400}{\sqrt{3}}~\text{m/s}\) | 4. | \(\dfrac{100}{\sqrt{5}}~\text{m/s}\) |
Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom. The gas is maintained at a temperature of \(T.\) The total internal energy, \(U\) of a mole of this gas, and the value of \(\gamma~\left(=\dfrac{C_P}{C_V}\right )\) are, respectively:
1. \( U=5 R T \text { and } \gamma=\dfrac{7}{5} \)
2. \( U=\dfrac{5}{2} R T \text { and } \gamma=\dfrac{6}{5} \)
3. \(U=5 R T \text { and } \gamma=\dfrac{6}{5} \)
4. \( U=\dfrac{5}{2} R T \text { and } \gamma=\dfrac{7}{5}\)
Initially, a gas of diatomic molecules is contained in a cylinder of volume \(V_1\) at a pressure \(P_1\) and temperature \(250~\text{K}.\) Assume that \(25\%\) of the molecules get dissociated, causing a change in the number of moles. The pressure of the resulting gas at temperature \(2000~\text{K},\) when contained in a volume \(2V_1\) is given by \(P_2.\) The ratio \(P_2/P_1\) is:
1. \(2\)
2. \(3\)
3. \(5\)
4. \(9\)
The temperature of an open room of volume \(30~\text{m}^3\) increases from \(17^\circ \text{C}\) to \(27^\circ \text{C}\) due to the sunshine. The atmospheric pressure in the room remains \(1\times 10^{5}~\text{Pa}\). In \(n_i\) and \(n_f\) are the number of molecules in the room before and after heating, the \(n_f\text-n_i \) will be:
1. \( -1.61 \times 10^{23} \)
2. \( 1.38 \times 10^{23} \)
3. \( 2.5 \times 10^{25} \)
4. \( -2.5 \times 10^{25}\)
The internal energy (\(U\)), pressure (\(P\)), and volume (\(V\)) of an ideal gas are related as \(U=3PV+4\). The gas is:
| 1. | Diatomic only |
| 2. | Polyatomic only |
| 3. | Either monoatomic or diatomic |
| 4. | Monoatomic only |
If the ratio of the number density per cm3 of the two gases is \(5:3\) and the ratio of the diameters of the molecules of the two gases is \(4:5,\) then, the ratio of the mean free path of molecules of two gases is:
| 1. | \(\dfrac{16}{15}\) | 2. | \(\dfrac{15}{16}\) |
| 3. | \(\dfrac{3}{4}\) | 4. | \(\dfrac{4}{3}\) |
The mass of a hydrogen molecule is \(3.32 \times 10^{-27}~\text{kg}.\) If \(10^{23}\) hydrogen molecules strike, per second, a fixed wall of area \(2~\text{cm}^2\) at an angle of \(45^\circ\) to the normal, and rebound elastically with a speed of \(10^3~\text{m/s},\) then the pressure on the wall is nearly:
1. \( 2.35 \times 10^3 ~\text{N/m}^2 \)
2. \(4.70 \times 10^3 ~\text{N/m}^2 \)
3. \(2.35 \times 10^2 ~\text{N/m}^2 \)
4. \(4.70 \times 10^2 ~\text{N/m}^2 \)
Two moles of an ideal monoatomic gas occupy a volume \(V\) at \(27^\circ \text{C}\). The gas expands adiabatically to a volume \(2V\). Calculate the final temperature of the gas and the change in its internal energy:
1. \(189~\text{K}, ~2.7~\text{kJ}~\)
2. \(195~\text{K}, ~-2.7~\text{kJ}~\)
3. \(189~\text{K}, ~-2.7~\text{kJ}~\)
4. \(195~\text{K}, ~2.7~\text{kJ}~\)
Given below are two statements :
| Statement I: | In a diatomic molecule, the rotational energy at a given temperature obeys Maxwell's distribution. |
| Statement II: | In a diatomic molecule, the rotational energy at a given temperature equals the translational kinetic energy for each molecule. |
In the light of the above statements, choose the correct answer from the options given below :
| 1. | Statement I is false but Statement II is true. |
| 2. | Both Statement I and Statement II are false. |
| 3. | Both Statement I and Statement II are true. |
| 4. | Statement I is true but Statement II is false. |