The density of water is \(1000~\text{kg/m}^{3}.\) The density of water vapour at \(100^{\circ}\text{C}\) and \(1\) atm pressure is \(0.6~\text{kg/m}^{3}.\) The volume of a molecule multiplied by the total number gives, what is called, molecular volume. The ratio (or fraction) of the molecular volume to the total volume occupied by the water vapour under the above conditions of temperature and pressure is:

A vessel contains two nonreactive gases: neon (monatomic) and oxygen (diatomic). The ratio of their partial pressures is \(3:2.\) The ratio of the number of molecules is:
(Atomic mass of Ne \(=20.2\) u, molecular mass of O₂ \(=32.0\) u)
1. \(2:3\)
2. \(3:2\)
3. \(1:3\)
4. \(3:1\)

A flask contains argon and chlorine in the ratio of \(2:1\) by mass. The temperature of the mixture is \(27~^\circ\mathrm{C}\). The ratio of average kinetic energy per molecule of the molecules of the two gases is: 
(Atomic mass of argon = \(39.9~\text{u}\); Molecular mass of chlorine = \(70.9~\text{u}\))
1. \(1:2\)
2. \(2:1\)
3. \(1:1\)
4. \(1:2\)

A flask contains argon and chlorine in the ratio of \(2:1\) by mass. The temperature of the mixture is \(27^{\circ}~\mathrm{C}\). The ratio of root mean square speed \(v_{rms}\) of the molecules of the two gases is: (Atomic mass of argon = \(39.9\) u; Molecular mass of chlorine = \(70.9\) u)
1. \(2.33\)
2. \(1.33\)
3. \(0.5\)
4. \(2\)

Uranium has two isotopes of masses \(235 \) and \(238\) units. If both are present in Uranium hexafluoride gas, which would have the larger average speed?
1. \(^{235} \mathrm{U} \mathrm{F}_{6}\)
2. \({}^{238} \mathrm{U} \mathrm{F}_{6}\)
3. Both will have the same average speed.
4. Data insufficient

When a molecule (or an elastic ball) hits a ( massive) wall, it rebounds with the same speed. When a ball hits a massive bat held firmly, the same thing happens. However, when the bat is moving towards the ball, the ball rebounds at a different speed. Does the ball move faster or slower? 
1. faster
2. slower
3. The speed of the ball does not change
4. none of these