CBSE Questions for Class 11 Engineering Physics Kinetic Theory Quiz 1 - MCQExams.com

An ideal gas goes through a reversible cycle $$a\rightarrow b\rightarrow c\rightarrow d$$ has the V- T diagram shown below. Process $$d\rightarrow a $$ and $$b\rightarrow c$$ are adiabatic.
The corresponding P-V diagram for the process is ( all figure are schematic and not drawn to scale).
306918.png
In the nuclear fusion reaction, $$_{1}^{2}\mathrm{H}+_{1}^{3}\mathrm{H}\rightarrow_2^4{He}$$ $$+\ {n}$$ given that the repulsive potential energy between the two nuclei is $$7.7\times 10^{-14}\ {J}$$, the temperature at which the gases must be heated to initiate the reaction is nearly [Boltzmann's constant $$\mathrm{k}=1.38\times 10^{-23}\mathrm{J}/\mathrm{K}$$]
  • $$10^{7}\ {K}$$
  • $$10^{5}\ {K}$$
  • $$10^{3}\ {K}$$
  • $$10^{9}\ {K}$$
An ideal gas is enclosed in a cylinder at pressure of $$2 \,atm$$ and temperature, $$300 \,K$$. The mean time between two successive collisions is $$6 \times 10^{-8} \,s$$. If the pressure is doubled and temperature is increased to $$500 \,K$$, the mean time between two successive collisions will be close to:
  • $$4 \times 10^{-8} \,s$$
  • $$3 \times 10^{-6} \,s$$
  • $$2 \times 10^{-7} \,s$$
  • $$0.5 \times 10^{-8} \,s$$
$$'N'$$ moles of a diatomic gas in a cylinder are at a temperature $$'T'$$. Heat is supplied to the cylinder such that the temperature remains constant but n moles of the diatomic gas gets converted into monatomic gas. What is the change in the total kinetic energy of the gas ?
  • $$\dfrac{5}{2}nRT$$
  • $$\dfrac{1}{2}nRT$$
  • $$0$$
  • $$\dfrac{3}{2}nRT$$
Which of the following shows the correct relationship between the pressure $$'P'$$ and density $$\rho$$ of an ideal gas at constant temperature ? 
Two non-reactive monoatomic ideal gases have their atomic masses in the ratio 2:The ratio of their partial pressures, when enclosed in a vessel kept at a constant temperature, is 4:The ratio of their densities is
  • 1 : 4
  • 1 : 2
  • 6 : 9
  • 8 : 9
A gas molecule of mass $$M$$ at the surface of the Earth has kinetic energy equivalent to $$0^oC$$. If it were to go up straight without colliding with any other molecules, how high it would rise?
Assume that the height attained is much less than radius of the earth. ($$k_B$$ is Boltzmann constant)
  • $$0$$
  • $$\dfrac {273 k_B}{2 Mg}$$
  • $$\dfrac {546 k_B}{3 Mg}$$
  • $$\dfrac {819 k_B}{2 Mg}$$
  • Statement -1 is True, Statement-2 is True; Statement -2 is a correct explanation for Statement-1.
  • Statement -1 is True, Statement-2 is True; Statement -2 is NOT a correct explanation for Statement-1.
  • Statement -1 is True, Statement-2 is False
  • Statement -1 is False, Statement-2 is True.
The ratio of the specific heats $$\dfrac {C_p}{C_v}=\gamma$$ in terms of degree of freedom (n) is given by:
  • $$\left (1+\dfrac {2}{n}\right )$$
  • $$\left (1+\dfrac {n}{2}\right )$$
  • $$\left (1+\dfrac {1}{n}\right )$$
  • $$\left (1+\dfrac {n}{3}\right )$$
A given sample of an ideal gas occupies a volume V at a pressure P and absolute temperature T. The mass of each molecule of the gas is m. which of the following gives the density of the gas?
  • mKT
  • P/(kT)
  • Pm/(kT)
  • P/(kTV)
The amount of heat energy required to raise the temperature of 1 g of Helium at NTP, from $$T_{1}K$$ to $$T_{2}K$$ is
  • $$\displaystyle \frac{3}{8}N_{a}k_{B}(T_{2}-T_{1})$$
  • $$\displaystyle \frac{3}{2}N_{a}k_{B}(T_{2}-T_{1})$$
  • $$\displaystyle \frac{3}{4}N_{a}k_{B}(T_{2}-T_{1})$$
  • $$\displaystyle \frac{3}{4}N_{a}k_{B}\left ( \frac{T_{2}}{T_{1}} \right )$$
Degree of freedom for polyatomic gas is
  • $$\ge  4$$
  • $$\ge  5$$
  • $$\ge  6$$
  • $$\ge  7$$
A vessel of volume $$20\ L$$ contains a mixture of hydrogen and helium at temperature of $$27^{\circ}C$$ and pressure $$2\ atm$$. The mass of mixture is $$5\ g$$. Assuming the gases to be ideal, the ratio of mass of hydrogen to that of the helium in the given mixture will be
  • $$1 : 2$$
  • $$2 : 3$$
  • $$2 : 1$$
  • $$2 : 5$$

The difference between volume and pressure coefficients of an ideal gas is :


24920.PNG
  • $$\dfrac{1}{273}$$
  • $$273$$
  • $$\dfrac{2}{273}$$
  • Zero
The gas law $$\left [ \dfrac{PV}{T} \right ]=$$ constant is true for
  • isothermal change only
  • adiabatic change only
  • both isothermal & adiabatic
  • neither isothermal nor adiabatic

The temperature of a gas contained in a closed vessel is increased by 2 K when the pressure is increased by 2%. The initial temperature of the gas is :
  • 200K
  • 100K
  • 200$$^{0}$$C
  • 100$$^{0}$$C

The mass of oxygen gas (in Kilo grams) occupying a volume of 11.2 litre at a temperature 27$$^{0}$$C and a pressure of 76cm of mercury is :

(Molecular weight of oxygen = 32)
  • 0.001456
  • 0.01456
  • 0.1456
  • 1.1456
From what minimum height, a block of ice has to be dropped in order that it may melt completely on hitting the ground :
  • $$mgh$$
  • $$\dfrac{mgh}{l}$$
  • $$\dfrac{l}{g}$$
  • $$\dfrac{h}{lg}$$
If for a gas $$\dfrac{R}{C_{v}}=0.67$$, then the gas is made up of molecules which are :
  • Diatomic
  • Monoatomic
  • Polyatomic
  • Mixture of Diatomic & Polyatomic

The P-T graph for the given mass of an ideal gas is shown in figure. Then the volume


24918.PNG
  • increases
  • decreases
  • remains constant
  • data insufficient

A gas in an airtight container is heated from 25$$^{o}$$C to 90$$^{o}$$C. The density of gas will :


24912_3be3ef5bf04d4f9899cb7551ad4cecc0.png
  • increase slightly
  • increase considerably
  • remain the same
  • decrease slightly

The molar gas constant is the same for all gases because at the same temperature and pressure, equal volumes of gases have the same :


24890_63dab1df5b28479dacf92fc02db26c12.png
  • number of molecules
  • average potential energy
  • ratio of specific heats
  • density

If the volume of the gas is to be increased by 4 times :
  • temperature and pressure must be doubled
  • at constant P, the temperature must be increased by 4 times
  • at constant T, the pressure must be increased by 4 times
  • it cannot be increased

Three closed vessels A, B and C are at the same temperature T and contain gases which obey Maxwell distribution law of velocities. Vessel A contains $$O_2$$, B only $$N_2$$ and C mixture of equal quantities of $$O_2$$ and $$N_2$$. If the average speed of $$O_2$$ molecules in vessel A is $$V_1$$ and that of $$N_1$$ molecules in vessel B is $$V_2$$, then the average speed of the $$O_2$$ molecules in vessel C is
  • $$\frac{{({v_1} + {v_2})}}{2}$$
  • $$V_1$$
  • $$\sqrt {{v_1}{v_2}} $$
  • None of these

A gas at temperature 27$$^{0}$$C and pressure 30 atmospheres is allowed to expand to one atmospheric pressure. If the volume becomes 10 times its initial volumes, the final temperature becomes :
  • 100$$^{o}$$C
  • 373 K
  • 373$$^{o}$$C
  • -173$$^{o}$$C

The Universal gas constant may be expressed as :

a) 8.31 J/mole-K         c) 2.00 J/mole-K

b) 8.31 cal/mole-K       d) 2.00 cal/mole-K
  • a,c
  • a,d
  • b,c
  • b,d

The parameter that determine the physical state of gas are :

a) Pressure                  b) Volume

c) Number of moles    d) Temperature
  • a & b
  • a,b & c
  • a,b & d
  • a,c & d
State whether true or false.
The arrangement of particles in a liquid is less ordered compared to solids. However, there is no order in the arrangement of particles in the gaseous state.
  • True
  • False

16 gm of $$O_{2}$$ gas and x gm of $$H_{2}$$ gas occupy the same volume at the same temperature and pressure. Then x is :
  • 1/2gm
  • 1gm
  • 8gm
  • 16 gm

Select the correct formula :

(where k=Boltzmann's constant, R= gas constant, n= moles, r = density, M= molecular weight, p= pressure, T= kelvin temperature, V= volume)

a) k=RN$$_{av}$$

b)$$r=\dfrac{nM}{V}$$

c)$$\dfrac{p}{r}=\dfrac{RT}{M}$$

d) R=kN$$_{av}$$
  • a,b,c
  • a,b,d
  • b,c,d
  • a,c,d

In the equation PV=constant, the numerical value of constant depends upon

a) temperature                 b) mass of the gas

c) system of units used   d) nature of the gas
  • a & b
  • b & c
  • c & d
  • all
State whether true or false.
Sponge though compressible, is a solid.
  • True
  • False

Two containers of equal volume containing the same gas at pressure $$P_{1}$$ and  $$P_{2}$$ and absolute temperature  $$T_{1}$$ and  $$T_{2}$$ respectively were connected with narrow capillary tube. The gas reaches a common pressure P and a common temperature T. The ratio P/T is equal to :
  • $$\dfrac{P_{1}}{T_{1}} +\dfrac{P_{2}}{T_{2}}$$
  • $$\dfrac{1}{2}\left ( \dfrac{P_{1}}{T_{1}} +\dfrac{P_{2}}{T_{2}}\right )$$
  • $$\dfrac{P_{1}T_{2}+P_{2}T_{1}}{T_{1}+T_{2}}$$
  • $$\dfrac{P_{1}T_{2}-P_{2}T_{1}}{T_{1}-T_{2}}$$
The value of $$\gamma$$ for gas X is 1.66, then x is :
  • Ne
  • O$$_3$$
  • N$$_2$$
  • H$$_2$$
According to the Boltzmann's law of equipartition of energy, the energy per degree of freedom and at a temperature T K is :
  • (3/2) KT
  • (2/3) KT
  • KT
  • 1/2 KT
When the pressure of a gas is changed, then:
  • The density of the gas also changes.
  • The ratio of the pressure to the density remains unaffected.
  • The velocity of the sound remains unaffected.
  • The value of $$\gamma$$ changes.
A system consists of N particles, which have independent K relations among one another. The number of degrees of freedom of the system is given by :
  • 3 NK
  • N/3K
  • 3 N/K
  • 3N - K
The value of C$$_v$$ for 1 mol of polyatomic gas is (F $$=$$ number of degrees of freedom) :
  • $$\displaystyle \frac{fR}{2T}$$
  • $$\displaystyle \frac{fR}{2}$$
  • $$\displaystyle \frac{fRT}{2}$$
  • $$2fRT$$
A man is climbing up a spiral type staircase. His degrees of freedom are :
  • 1
  • 2
  • 3
  • more than 3
The law of equipartition of energy was given by :
  • Claussius
  • Maxwell
  • Boltzmann
  • Carnot
If the number of molecules in a gas is N then the number of molecules moving in negative X-direction will be :
  • N/6
  • N/4
  • N/3
  • N
At what temperature will the kinetic energy of gas molecules be double of its value at 27$$^o$$C?
  • $$54^oC$$
  • $$108^oC$$
  • $$300^oC$$
  • $$327^oC$$
The internal energy of a monoatomic ideal gas is :
  • only kinetic
  • only potential
  • partly kinetic and partly potential
  • none
Keeping the number of moles, volume and temperature the same, which of the following are the same for all ideal gases?
  • rms speed of molecules
  • Density
  • Pressure
  • Average magnitude of momentum
Which of the following is/are true on the basis of kinetic theory of matter?
  • Solids have a definite volume and definite shape
  • Liquids have a definite volume, but no definite shape
  • Gases have no definite volume and no definite shape
  • All of the above
Solids have :
  • definite mass
  • definite volume
  • both A & B
  • none
The amount of heat required to heat 1 mol of a monoatomic gas from 200$$^o$$C to 250$$^o$$C will be ............. if the heat required to heat the diatomic gas from 200$$^o$$C to 300$$^o$$C is Q.
  • 2Q/3
  • 3Q/5
  • 3Q/10
  • 2Q/5
On the basis of kinetic theory of matter :
  • the solids have a definite volume and definite shape
  • the liquids have a definite volume but no definite shape
  • the gases have no definite volume and no definite shape
  • all of the above 
The inter-molecular spaces in a liquid is :
  • less than a solid
  • more than a gas
  • more than a solid
  • more than a solid and a gas
The correct relation connecting the universal gas constant (R), Avogadro number N$$_A$$ and Boltzmann constant (K) is :
  • $$R = NK^2$$
  • $$K = NR$$
  • $$N = RK$$
  • $$R=NK$$
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