CBSE Questions for Class 11 Engineering Physics Kinetic Theory Quiz 3 - MCQExams.com

Gas exerts pressure on the walls of container because the molecules-
  • Are loosing the kinetic energy
  • Are getting stuck to the walls
  • Are transferring their momentum to walls
  • Are accelerated toward walls.
At what temperature the kinetic energy of a gas molecular is one-half of its value of $${30}^\circ C$$ ?
  • $$151.5 K$$
  • $$251.5 K$$
  • $$303 K$$
  • $$121 K$$
The internal energy of a diatomic gas us given as $$U=U_0V$$, where $$U_0$$ is a constant . Molar heat capacity of gas is 
  • $$\dfrac{5}{2}R$$
  • $$\dfrac{7}{2}R$$
  • $$\dfrac{9}{2}R$$
  • $$\dfrac{3}{2}R$$
The number of molecules in 22.4 $$cm^{3}$$ of nitrogen gas at STP is __________.
  • $$6.023\times10^{20}$$
  • $$6.023\times10^{23}$$
  • $$22.4\times10^{20}$$
  • $$22.4\times10^{23}$$
A gas behaves more closely as an ideal gas at :
  • low pressure and low temperature
  • low pressure and high temperature
  • high pressure and low temperature
  • high pressure and high temperature
Which of the following gives evidence to kinetic theory of gases?
  • assumption of kinetic theory
  • Boyle's law
  • idea of mean free path
  • diffusion and evaporation
Significant motion for the molecules of a monoatomic gas corresponds to :
  • translatory
  • vibratory
  • rotatory
  • none of these
When 273c.c of a gas is heated through 10C. AT constant pressure.then its new volume will be .
  • 272 c.c
  • 273c.c
  • 274c.c
  • 275c.c
A gas will approach ideal behaviour at
  • low temperature and low pressure
  • low temperature and high pressure
  • high temperature and low pressure
  • high temperature and high pressure
The mean kinetic energy per mole of an ideal gas at $$0^oC$$ is a approximately :
  • $$3.4\ J$$
  • $$3.4\times 10^2\ J$$
  • $$3.4\times 10^3\ J$$
  • $$207\ J$$
The average thermal energy for a mono-atomic gas is : ($$K_{B}$$ is Boltzmann constant and $$T$$ is absolute temperature)
  • $$ \dfrac{3}{2} K_{B} T $$
  • $$ \dfrac{5}{2} K_{B} T $$
  • $$ \dfrac{7}{2} K_{B} T $$
  • $$ \dfrac{1}{2} K_{B} T $$
Every gas (real gas ) behaves as an ideal gas 
  • At high temperature and low pressure
  • At low temperature and high pressure
  • At normal temperature
  • None of the above
A 0.1kg steel ball falls from a height of 10m and bounces to a height of 7m. The rise in temperature of the ball is:
(Given, $$C=0.1kcal/kg/c^{0}$$)
  • $$0.05^{0}C$$
  • $$0.064^{0}C$$
  • $$0.06^{0}C$$
  • $$0.07^{0}C$$
A bullet travelling at 100 $$ms^{-1}$$ suddenly hits a concrete wall. If its K.E. is converted completely into heat, the raise in temperature is $$\left ( s=100Jkg^{-1}K^{-1} \right )$$ :
  • 20K
  • 40K
  • 50K
  • 60K
A piece of lead falls from a height of 100m on a fixed non-conducting slab which brings it to rest. The temperature of the lead piece immediately after collision increases by (Sp.heat of lead is 30.6cal/kg/$$^{0}C$$ and $$g=9.8m/sec^{2}.$$)
  • 0K
  • $$27^{0}C$$
  • 7.62K
  • 4.2K
A closed vessel contains some gas at a given temperature and pressure. If the vessel is given a very high velocity, the temperature of the gas
  • increases
  • decreases
  • may increase or decrease depending upon the nature of the gas
  • does not change
Two metal balls of same material having masses 50gm and 100gm collides with a target with same velocity. Then the ratio of their rise in temperature is

  • 1:2
  • 4:1
  • 2:1
  • 1:1
2kg of Ice block should be dropped from ‘x km’ height to melt completely. The 8 kg of ice block should be dropped from height
  • 4x km
  • x km
  • 2x km
  • 3x
From which height a block of ice must be dropped in order that it melts completely. Assume that all the energy is retained by the ice .
($$g=10ms^{-2}$$, $$L=80Jgm^{-1}$$and J $$=$$ 4.2 J/cal)
  • 1000Km
  • 100Km
  • 33.6Km
  • 1Km
The height of water fall is 210 m assuming that the surface on which the water is falling is perfectly insulated and all the kinetic energy of water is dissipated as heat. Find the rise in temperature of the water :
($$g=10m/s^{2}$$, Specific heat of water $$=1000 \ cal.Kg^{-1}C^{-1}$$ , 1 kcal$$=$$ 4200 J)
  • $$0.1^{0}C$$
  • $$0.5^{0}C$$
  • $$1^{0}C$$
  • $$0.25^{0}C$$
A bullet of mass $$10\times 10^{-3}\ kg$$ moving with a speed of $$20 ms^{-1}$$ hits an ice block $$(0^{o}c)$$ of $$990\ g$$  kept at rest on a frictionless floor and gets embedded in it. If ice takes $$50\%$$ of $$K.E$$, for melting, then the mass of the ice block that has melted is($$J=4.2 J/Cal$$) (Latent heat of ice $$=80\ cal/g$$)
  • $$6$$
  • $$3$$
  • $$6\times 10^{-3}$$
  • $$3\times 10^{-3}$$
Water is falling from 160m height. Assuming that half the K.E. of falling water gets converted into heat, the rise in temperature of water is approximately
  • $$0.1^{0}C$$
  • $$0.2^{0}C$$
  • $$0.3^{0}C$$
  • $$0.4^{0}C$$

The temperature of a gas is due to

  • P.E. of its molecules
  • K.E. of its molecules
  • Attractive forces between molecules
  • Repulsive forces between molecules

When the volume of a gas is decreased at constant temperature the pressure increases because the molecules

  • strike unit area of the walls of the container more often
  • strike the unit area of the walls of the container with higher speed
  • strike the unit area of the wall of the container with lesser speed
  • move with more kinetic energy

The graph between temperature and pressure of a perfect gas is

  • hyperbola.
  • parabola.
  • a straight line parallel to pressure axes at $$73^{0}C$$.
  • a straight line intercepting the temperature axes at $$273^{0}C$$.

The graph drawn between pressure and temperature at constant volume for a given mass of different molecular weights $$M_{1}$$ and $$M_{2}$$ are the straight lines as shown in the figure then 


24876_27fee15827074f81b52797da33a21666.png
  • $$M_{2} > M_{1}$$
  • $$M_{1} > M_{2}$$
  • $$M_{1} = M_{2}$$
  • $$M_{1}^{3} = M_{2}$$

At constant pressure, density of a gas is :


24875_9f3e8e410cb64c79a7b355df76a66bb4.png
  • directly proportional to absolute temperature
  • inversely proportional to absolute temperature
  • independent of temperature
  • directly proportional to square root of absolute temperature

Universal gas constant per molecule is called

  • Rydberg constant
  • Kelvin constant
  • Boltzman constant
  • Stefan's constant

All gasses deviate from gas laws at

  • high pressure and low temperature.
  • low pressure and high temperature.
  • high pressure and high temperature.
  • low pressure and low temperature.
Statement - I : The total translational kinetic energy of all the molecules of a given mass of an ideal gas is 1.5 times the product of its pressure and its volume because.
Statement - II : The molecules of a gas collide with each other and the velocities of the molecules change due to the collision.

  • 1) Statement - I is true, Statement - II is true; statement - II is a correct explanation for statement - I
  • 2) Statement - I is true, statement - II is true; statement - II is NOT a correct explanation for statement - I
  • 3) statement - I is true, statement - II is false
  • 4) statement - I is false, statement - II is true

If the slope of P-T graph for a given mass of a gas increases, then the volume of the gas


24878.PNG
  • Increases
  • Decreases
  • Does not change
  • May increase or decrease

An ideal gas is that which


24882_71e899ff5a1b4186aedf17254c1e26d0.png
  • Cannot be liquified
  • Can be easily liquified
  • Has strong inter molecular forces
  • Has a large size of molecules.

A box contains x molecules of a gas. How will the pressure of the gas be affected if the number of molecules is made 2x?

  • Pressure will decrease.
  • Pressure will remain unchanged.
  • Pressure will be doubled.
  • Pressure will become three times.

In a gas equation, PV = RT, V refers to the volume of:

  • any amount of a gas
  • one gram mass of a gas
  • one gram mole of gas
  • one litre of gas

The relation between volume V, pressure P and absolute temperature T of an ideal gas is PV = xT, where x is a constant. The value of x depend upon

  • the mass of the gas molecule
  • the average kinetic energy of the gas molecules
  • P, V and T
  • the number of gas molecules in volume V.

The density of an ideal gas

  • is directly proportional to its pressure and absolute temperature
  • is directly proportional to its pressure and inversely proportional to its absolute temperature
  • is inversely proportional to its pressure and directly proportional to its absolute temperature
  • is inversely proportional to both its pressure and absolute temperature of the gas

Choose the only correct statement from the following 

  • The pressure of a gas is equal to the total kinetic energy of the molecules in a unit volume of the gas.
  • The product of pressure and volume of a gas is always constant.
  • The average kinetic energy of molecules of a gas is proportional to its absolute temperature.
  • The average kinetic energy of molecules of a gas is proportional to the square root of its absolute temperature.

If pressure and temperature of an ideal gas are doubled and volume is halved, the number of molecules of the gas

  • becomes half
  • becomes two times
  • becomes 4 times
  • remains constant

The absolute temperature T of a gas is plotted against its pressure P for two different constant volumes V$$_{1}$$ and V$$_{2}$$  where V$$_{1}$$ > V$$_{2}$$. T is plotted along x-axis and P along y-axis.

  • Slope for curve corresponding to volume V$$_{1}$$ is greater than that corresponding to volume V$$_{2}$$.
  • Slope for curve corresponding to volume V$$_{2}$$ is greater than that corresponding to volume V$$_{1}$$.
  • Slope for both curves are equal.
  • Slope for both curves are unequal such that they intersect at T = 0.

The universal gas constant has the units

  • dyne/$$^{0}C$$
  • erg/mole/k
  • erg-cm/k
  • watt/k

The average velocity of the molecules in a gas in equilibrium is

  • proportional to $$\sqrt{T}$$
  • proportional to T
  • proportional to $$T^{2}$$
  • equal to zero

Equation of gas in terms of pressure $$p$$ absolute temperature $$T$$ and density $$d$$ is :

  • $$\dfrac{p_{1}}{d_{1}T_{1}}=\dfrac{p_{2}}{d_{2}T_{2}}$$
  • $$\dfrac{p_{1}T_{1}}{d_{1}}=\dfrac{p_{2}T_{2}}{d_{2}}$$
  • $$\dfrac{p_{1}d_{2}}{T_{2}}=\dfrac{p_{2}d_{1}}{T_{1}}$$
  • $$\dfrac{p_{1}d_{1}}{T_{1}}=\dfrac{p_{2}d_{2}}{T_{2}}$$

The density of air at N.T.P. is $$1.293 gm/lit$$. If the pressure is tripled keeping its temperature constant its density becomes

  • $$3.87 gm/ltr$$
  • $$1.293gm/ltr$$
  • $$2.586 gm/ltr$$
  • $$0.431 gm/ltr$$

A gas is kept at 13$$^{0}$$C in a vessel. If the volume of the gas is kept constant and is heated, the pressure will be doubled to its initial pressure at a temperature

  • 572 K
  • 286 K
  • 143 K
  • 73 K

A bubble rises from the bottom of a lake, 90m deep. On reaching the surface, its volume becomes(take atmospheric pressure equals to 10 m of water )

  • 4 times
  • 8 times
  • 10 times
  • 3 times

A cylinder contains a gas at temperature of 27$$^{0}$$and a pressure 1MPa. If the temperature of the gas is lowered to -23$$^{0}$$ C , the change in pressure is

  • 1MPa
  • 5/6MPa
  • 1/6MPa
  • 5MPa

A volume 'V' and temperature 'T' was obtained, as shown in the diagram, when a given mass of gas was heated. During the heating process, the pressure is


24913.PNG
  • increased
  • decreased
  • remains constant
  • changed erratically

A gas at 627$$^{0}$$ C is cooled so that its pressure becomes $$\dfrac{1}{3}$$ of its initial value at constant volume. Its final temperature is 

  • 900 K
  • 600 K
  • 300 K
  • 100K

At 27$$^{0}$$ C certain gas occupied a volume of 4 litres. If the volume of this is to be increased to 12 litres at the same pressure, the gas is to be heated to a temperature

  • 300 K
  • 900 K
  • 600 K
  • 1200K

A P-V diagram is obtained by changing the temperature of the gas as shown. During this process the gas is :


24914.PNG
  • heated continuously
  • cooled continuously
  • heated in the beginning but cooled towards the end
  • cooled in the beginning but heated towards the end
0:0:1


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