Q.1
In the following questions, a statement of assertion is followed by a statement of reason. You are required to choose the correct one out of the given four responses and mark it as (a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: The ratio Cp/Cv is more for helium gas than for hydrogen gas. Reason: ATomic mass of helium is more than that of Hydrogen
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.2
The rate of diffusion, is
  • equal in solids, liquids, and gases
  • faster in liquids than in solids and gases
  • faster in solids than in liquids and gases
  • faster in gases than liquids and solids
Q.3
Two balloons are filled, on with pure He gas and other by air, respectively. If the pressure and temperature of these balloons are same then the number of molecules per unit volume is
  • more in the He filled balloon
  • same in both balloons
  • more in air-filled balloon
  • in the ratio of 1: 4
Q.4
If one mole of monoatomic gas( $\gamma =5/3$) is mixed with one mole of a diatomic gas ($\gamma = 7/5$), the value of adiabatic exponent $\gamma$ for mixture is
  • 1.35
  • 1.40
  • 1.5
  • 1.75
Q.5
A thermally insulated vessel contains an ideal gas of Molecular mass M and a ratio of specific heats $\gamma$. It is moving with speed b and is suddenly brought to rest.Assuming no heat lost to the surroundings, its temperature increases by
  • $ \frac { (\gamma -1}{2(\gamma + 2)R} Mv^2 \; K$
  • $ \frac { (\gamma -1}{2\gamma R} Mv^2 \; K$
  • $ \frac { \gamma Mv^2} {2R} \; K$
  • $ \frac { (\gamma -1}{2 R} Mv^2 \; K$
Q.6
A gas behaves as an ideal gas at
  • high pressure and low temperature
  • low pressure and high temperature
  • high pressure and high temperature
  • low pressure and low temperature
Q.7
If the rms velocity of the molecules of a gas in a container be doubled then pressure of the gas will
  • becomes 4 times of its previous value
  • becomes 2 times of its previous value
  • remains same
  • becomes 1/4 of its previous value
Q.8
In a vessel , the gas is at a  pressure P. If the mass of all the molecules is halved  and their speed is doubled, then the resultant pressure will be
  • 4P
  • 2P
  • P
  • P/2
Q.9
On colliding in a closed container the gas molecules
  • transfer momentum to the walls
  • momentum becomes zero
  • momentum becomes zero
  • perform brownian motion
Q.10
The degree of Freedom of a triatomic gas is
  • 1
  • 2
  • 6
  • 8
Q.11
The root mean square and most probable speed of the molecules in a gas are
  • same
  • different
  • cannot say
  • depends on nature of the gas
Q.12
In the following questions, a statement of assertion is followed by a statement of reason. You are required to choose the correct one out of the given four responses and mark it as (a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: The ratio Cp/Cv for a diatomic gas is more than that for a monatomic gas. Reason: The molecules of a monatomic gas have more degrees of freedom than those of a diatomic gas.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.13
In the following questions, a statement of assertion is followed by a statement of reason. You are required to choose the correct one out of the given four responses and mark it as (a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: The root mean square and most probable speeds of the molecules in a gas are the same. Reason: The Maxwell distribution for the speed of molecules in a gas is symmetrical.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.14
In the following questions, a statement of assertion is followed by a statement of reason. You are required to choose the correct one out of the given four responses and mark it as (a) If both assertion and reason are true and reason is the correct explanation of the assertion. (b) If both assertion and reason are true but reason is not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false. Assertion: Root mean square velocity of the gas does not change in an Isothermal process Reason: Isothermal process may be achieved by immersing the system in a large reservoir and performing the process slowly
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.15
A cubical box of side 1 meter contains helium gas (atomic weight 4) at a pressure of 100 N/mDuring an observation time of 1 second, an atom travelling with the root-mean-square speed parallel to one of the edges of the cube, was found to make 500 hits with a particular wall, without any collision with other atoms. Take R=25/3 J/mol-K and $k=1.38 \times 10^{−23}$ J/K. Evaluate the temperature of the gas
  • 120 K
  • 200 K
  • 160 K
  • 150 K
Q.16
Evaluate the average KE  per atom
  • $3.312 \times 10^{-21} $J
  • $2.312 \times 10^{-21} $J
  • $3.312 \times 10^{21} $J
  • $3.312 \times 10^{-23} $J
Q.17
Evaluate the total mass of the helium gas
  • $ 3 \times 10^{-4}$ kg
  • $ 2 \times 10^{-4}$ kg
  • $ 4 \times 10^{-4}$ kg
  • $ 5 \times 10^{-4}$ kg
Q.18
For Boyle’s law to hold good, the gas should be
  • perfect and at constant temperature but variable mass
  • perfect and of constant mass and temperature
  • real and at constant temperature but variable mass
  • real and of constant mass and temperature.
Q.19
A vessel of volume V contains a mixture of 1 mole of Hydrogen and 1 mole of Oxygen (both considered as ideal). Let f1(v)dv, denote the fraction of molecules with speed between v and (v + dv) with f2 (v)dv, similarly for oxygen. Then
  • f1(v) + f2 (v) =f(v) obeys the Maxwell’s distribution law.
  • f1(v), f2(v) will obey the Maxwell’s distribution law separately.
  • Neither f1 (v), nor f2 (v) will obey Maxwell’s distribution law.
  • f2(v) and f1 (v) will be the same
Q.20
When an ideal gas is compressed adiabatically, its temperature rises: the molecules on average have more kinetic energy than before. The kinetic energy increases
  • because of collisions with moving parts of the wall only.
  • because of collisions with the entire wall.
  • because the molecules gets accelerated in their motion inside the volume
  • because of the redistribution of energy amongst the molecules.
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