CBSE Questions for Class 11 Engineering Physics Kinetic Theory Quiz 8 - MCQExams.com

To what temperature should the hydrogen at $$327^oC$$ be cooled at constant pressure, so that the root mean square velocity of its molecules becomes half of its previous value?
  • $$-123^oC$$
  • $$123^oC$$
  • $$-100^oC$$
  • $$0^oC$$
The average kinetic energy of a gas molecule at $${27}^{o}C$$ is $$6.21\times {10}^{-21}J$$, then its average kinetic energy at $${227}^{o}C$$ is:
  • $$10.35\times {10}^{-21}J$$
  • $${11.35}\times {10}^{-21}J$$
  • $$52.2\times {10}^{-21}J$$
  • $$5.22\times {10}^{-21}J$$
$$3$$ moles of mono-atomic gas ($$\gamma=5/3$$) is mixed with $$1$$ mole of a diatomic gas ($$\gamma=7/3$$). The value of $$\gamma$$ for the mixture will be
  • $$\cfrac{9}{11}$$
  • $$\cfrac{11}{7}$$
  • $$\cfrac{12}{7}$$
  • $$\cfrac{15}{7}$$
Kinetic energy of a gas molecule depends on :
  • Volume
  • Temperature
  • Pressure
  • None of these
Rate of diffusion is: 
  • Faster in liquids than in solids and gases
  • Faster in gases than in liquids and solids
  • Faster in solids than in liquids and gases
  • None of these
Which of the following postulate of kinetic theory of matter states that collisions are perfectly elastic? 
  • Gas molecules are in constant random motion
  • When collisions occur, the molecules lose no kinetic energy
  • Molecules can collide with each other and with the walls of the container
  • All of above
If the pressure of the gas contained in a vessel is increased by $$0.4$$%, when heated through $$\displaystyle { 1 }^{ \circ  }C$$. What is the initial temperature of the gas?
  • $$\displaystyle 250K$$
  • $$\displaystyle { 250 }^{ \circ }C$$
  • $$\displaystyle 2500K$$
  • $$\displaystyle { 25 }^{ \circ }C$$
Which of the following is a postulate of kinetic theory of matter?
  • All gases at a given temperature have the same average kinetic energy.
  • Lighter gas molecules move faster than heavier molecules.
  • The kinetic energy of a gas is a measure of its Kelvin temperature.
  • All of the above
The molecules
  • in solid, liquid and gas, move freely anywhere.
  • in a solid, move freely within its boundary.
  • in a liquid, move within its boundary.
  • in a gas, move only within its boundary.
The average kinetic energy of all the molecules is assumed to be:
  • inversely proportional to the absolute temperature of the gas
  • directly proportional to the absolute temperature and size of the gas
  • directly proportional to the absolute temperature of the gas
  • not related to the absolute temperature of the gas
An ideal gas is heated in a container that has a fixed volume. Identify which of the following will increase as a result of this heating?
I. The pressure against the walls of the container
II. The average kinetic energy of the gas molecules
III. The number of moles of gas in the container
  • I only
  • I and II only
  • II and III only
  • II only
  • III only
A flask contains argon and chlorine in the ratio of $$2:1$$ by mass. The temperature of the mixture is $$27^0C$$. The ratio of average kinetic energies of two gases per molecule is
  • $$1:1$$
  • $$2:1$$
  • $$3:1$$
  • $$6:1$$
The kinetic particle theory explains the:
  • properties of the different states of matter
  • size and rigidity of different states of matter
  • reaction of matter
  • all of above
At $$\displaystyle { 10 }^{ \circ  }C$$, the value of the density of a fixed mass of an ideal gas divided by its pressure is $$'x'$$, at $$\displaystyle { 110 }^{ \circ  }C$$ this ratio is:
  • $$\displaystyle \frac { 10 }{ 110 } x$$
  • $$\displaystyle \frac { 383 }{ 283 } x$$
  • $$\displaystyle \frac { 110 }{ 10 } x$$
  • $$\displaystyle \frac { 283 }{ 383 } x$$
The temperature of a body is an indicator of :
  • The total energy of the moelcules of an object
  • The average energy of the molecules of an object
  • The total velocity of the molecules of the object
  • The average kinetic energy of the molecules of an object
A closed container of volume V contains an ideal gas at pressure P and Kelvin Temperature T. The temperature of the gas is changed to 4T due to passing heat to the container. Choose correct pairs of pressure and volume after change of the temperature.
  • $$P\;and \;V$$
  • $$\displaystyle P\;and \frac{1}{2}V$$
  • $$4\;P\;and \;4\;V$$
  • $$4\;P\;and \;V$$
  • $$\displaystyle \frac{1}{4}\;P\;and\;V$$
The number of vibrational degrees of freedom for a $$CO_2$$ molecule is
  • 4
  • 5
  • 6
  • 9
A  gas in a flexible container initially has volume of 320 L. If we decrease the pressure of the gas from 4.0 atm to 1.0 atm and decrease the temperature form 273 degrees Celsius to 0 degrees Celsius, what is the new volume of the gas?
  • 0 L
  • 320 L
  • 160 L
  • 640 L
  • 80 L
A closed container of a gas is heated to a high temperature. What do you predict will happen?
  • The gas particles will repel each other
  • The gas particles inside the container will move slower and slower
  • The pressure inside the container will decrease
  • The pressure inside the container will increase
During an experiment an ideal gas is found to obey an additional law $$V{p}^{2}=$$ constant. The gas is initially at temperature $$T$$ and volume $$V$$, when it expands to volume $$2V$$, the resulting temperature is $$T_2$$:
  • $$\cfrac { T }{ 2 } $$
  • $$2T$$
  • $$\sqrt { 2 } T $$
  • $$\cfrac { T }{ \sqrt { 2 } } $$
One mole of an ideal monoatomic gas is heated at a constant pressure from $$0^oC$$ to $$100^oC$$. Then the change in the internal energy of the gas is (Given $$R = 8.32 {Jmol}^{-1}K^{-1}$$)
  • $$0.83 \times 10^3 J$$
  • $$4.6 \times 10^3 J$$
  • $$2.08 \times 10^3 J$$
  • $$1.25 \times 10^3 J$$
In a thermodynamic process, helium gas obeys the law, $$T\ P^{-2/5} =$$ constant. The heat is given to $$n$$ moles of $$He$$ in order to raise the temperature from $$T$$ to $$2T$$ is :
  • $$8 RT$$
  • $$4 RT$$
  • $$16 RT$$
  • $$Zero$$
Identify the best graph which represents the relationship between the average kinetic energy of the molecules of a gas and its temperature?
For polyatomic molecules having 'f' vibrational modes, the ratio of two specific heats, $$\dfrac{C_p}{C_v}$$ is ............
  • $$\dfrac{1+f}{2+f}$$
  • $$\dfrac{2+f}{3+f}$$
  • $$\dfrac{4+f}{3+f}$$
  • $$\dfrac{5+f}{4+f}$$
If the potential energy of a gas molecule is $$U=\dfrac{M}{r^6}-\dfrac{N}{r^{12}}, M$$ and $$N$$ being positive constants, then the potential energy at equilibrium must be
  • Zero
  • $$NM^2/4$$
  • $$MN^2/4$$
  • $$M^2/4N$$
An ideal gas follows a process described by $$PV^2=C$$ from $$(P_1, V_1, T_1)$$ to $$(P_2, V_2, T_2)$$ (C is a constant). Then.
  • If $$P_1 > P_2$$ then $$T_2 > T_1$$
  • If $$V_2 > V_1$$ then $$T_2 < T_1$$
  • If $$V_2 > V_1$$ then $$T_2 > T_1$$
  • If $$P_1 > P_2$$ then $$V_2 > V_2$$
The number of degrees of freedom for a rigid diatomic molecule is ____________.
  • $$3$$
  • $$5$$
  • $$6$$
  • $$7$$
At what temperature hydrogen molecules will escape from the earth's surface?
(Take mass of hydrogen molecule $$ = 0.34 \times 10^{-26} $$ kg, Boltzman constant $$ = 1.38 \times 10^{-23} $$ J/K, radius of the earth $$ = 6.4 \times 10^{6} $$ and acceleration due to gravity $$ = 9.8 m/s^2 $$
  • 10 K
  • $$ 10^2 K $$
  • $$ 10^3 K $$
  • $$ 10^4 K $$
The mean energy of a molecule of an ideal gas is
  • $$KT$$
  • $$\dfrac { 1 }{ 2 } KT$$
  • $$\dfrac { 3 }{ 2 } KT$$
  • $$2 KT$$
If a gas mixture contains 2 moles of $$O_2$$ and 4 moles of Ar at temperature $$T$$, then what will be the total energy of the system (neglecting all vibrational modes)
  • 11 RT
  • 15 RT
  • 8 RT
  • RT
The average kinetic energy of thermal neutron is of the order of :
(Boltzmann's constant $${ k }_{ B }=8\times { 10 }^{ -5 }{ eV }/{ K }$$)
  • $$0.03 eV$$
  • $$3 eV$$
  • $$3 keV$$
  • $$3 MeV$$
$$4.48L$$ of an ideal gas at STP requires $$12cal$$ to raise the temperature by $${15}^{o}C$$ at constant volume. The $${C}_{P}$$ of the gas is ______ cal.
  • 2
  • 4
  • 6
  • 8
A vessel contains a mixture of one mole of oxygen and two moles of nitrogen at $$300\ K$$. The ratio of the average rotational kinetic energy per $$O_{2}$$ molecule to per $$N_{2}$$ molecule is
  • $$1 : 1$$
  • $$1 : 2$$
  • $$2 : 1$$
  • Depends on the moments of inertia of the two molecules
The speed of sound in hydrogen at NTP 1270 m/s. Then, the speed in a mixture of hydrogen and oxygen in the ratio 4 : 1 by volume will be :
  • 317 m/s
  • 635 m/s
  • 830 m/s
  • 950 m/s
In Mayer's realation
$${ C }_{ P }-{ C }_{ V }=R$$
'$$R$$' stands for:
  • translational kinetic energy of $$1$$ mol of gas
  • rotational kinetic energy of $$1$$ mol gas
  • vibratonal kinetic energy of $$1$$ mol gas
  • work done to increase the temperature of $$1$$ mol gas by one degree
If at the same temperature and pressure, the densities of two diatomic gases are $${ d }_{ 1 }$$ and $${ d }_{ 2 }$$ respectively, the ratio of mean kinetic energy per molecule of gases will be :
  • $$1 : 1$$
  • $${ d }_{ 1 }:{ d }_{ 2 }$$
  • $$\sqrt { { d }_{ 1 } } :\sqrt { { d }_{ 2 } } $$
  • $$\sqrt { { d }_{ 2 } } :\sqrt { { d }_{ 1 } } $$
$$4.48L$$ of an ideal gas at S.T.P requires $$12$$ calories to raise its temperature by $${15}^{o}C$$ at constant volume. The $${C}_{p}$$ of the gas is:
  • $$3cal$$
  • $$4cal$$
  • $$7cal$$
  • $$6cal$$
In Haber's process of ammonia manufacture:
$${ N }_{ 2 }(g)+3{ H }_{ 2 }(g)\longrightarrow 2{ NH }_{ 3 }(g)$$, $$\Delta { H }_{ { 25 }^{ o }C }^{ o }=-92.2kJ$$
Molecules$${N}_{2}(g)$$$${H}_{2}(g)$$$${NH}_{3}(g)$$
$${C}_{P}J{ K }^{ -1 }{ mol }^{ -1 }$$$$29.1$$$$28.8$$$$35.1$$
If $${C}_{P}$$ is independent of temperature,then reaction at $${100}^{o}C$$ compared to that of $${25}^{o}C$$ will be:
  • more endothermic
  • less endothermic
  • more exothermic
  • less exothermic
The mean kinetic energy of one mole of gas per degree of freedom (on the basis of kinetic theory of gases) is
  • $$\cfrac { 1 }{ 2 } kT$$
  • $$\cfrac { 3 }{ 2 } kT\quad $$
  • $$\cfrac { 3 }{ 2 } RT\quad $$
  • $$\cfrac { 1 }{ 2 } RT$$
Two identical containers P and Q with frictionless piston contain the same ideal gas at the same temperature and the same volume. The mass of gas in P is $$m_1$$ and that in Q is $$m_2$$. The gas in each cylinder is now allowed to expand isothermally to the same final volume $$1.5$$V. The changes pressure in P and Q are found to be $$\Delta$$p and $$2\Delta$$p respectively then.
  • $$\displaystyle m_2=2m_1$$
  • $$\displaystyle m_1 =2m_2$$
  • $$\displaystyle m_1=\frac{m_2}{4}$$
  • $$\displaystyle m_1m_2=1$$
X g of ice at $$0^o$$C is added to $$340$$g of water at $$20^o$$C. The final temperature of the resultant mixture is $$5^o$$C. The value of X (in g) is closest to. [Heat of fusion of ice$$=333\ J/g$$; Specific heat of water $$=4.184\ J/(g. K)$$].
  • $$80.4$$
  • $$52.8$$
  • $$120.6$$
  • $$60.3$$
Equal volumes of monoatomic and diatomic gases at the same temperature are given equal quantities of heat. Then,
  • the temperature of diatomic gas will be more
  • the temperature of monoatomic gas will be more
  • the temperature of both will be zero
  • nothing can be said
Match the List - I with List - II:
List-IList-II
(I) Translation kinetic energy $$\frac{3}{2}P$$
(II) Rotational kinetic energy of $$CO_2$$15/13
(III) Translation kinetic energy per unit volume7/5

(IV) $$\lambda$$ for $$CO_2$$ at very high temperature Function of T only
RT
$$\frac{3}{2} RT$$
  • (I) - 3 (II) - 4 (III) - 5 (IV) - 1
  • (I) - 4 (II) - 5 (III) - 1 (IV) - 2
  • (I) - 5 (II) - 6 (III) - 2 (IV) - 3
  • (I) - 6 (II) - 1 (III) - 3 (IV) - 4
The temperature at which the mean KE of the molecules of gas is one-third of the mean KE of its molecules at $$180^o C$$ is 
  • $$-122^o C$$
  • $$-90^o C$$
  • $$60^o C$$
  • $$151^o C$$
A diatomic gas is heated at certain pressure. What fraction of the heat energy is used to increase the internal energy?
  • $$3/5$$
  • $$3/7$$
  • $$5/7$$
  • $$5/9$$
If the average kinetic energy of a molecule of a hydrogen gas at $$300$$K is E, then the average kinetic energy of a molecule of a nitrogen gas at the same temperature is:
  • $$7$$E
  • $$E/14$$
  • $$14$$E
  • $$E/7$$
  • E
The gases are at absolute temperature $$300^oK$$ and $$350^oK$$ respectively. The ratio of average kinetic energy of their molecules is 
  • $$6:7$$
  • $$36:49$$
  • $$7:6$$
  • $$343: 216$$
A container is filled with $$20$$ moles of an ideal diatomic gas at absolute temperature $$T$$. When heat is supplied to gas, temperature remains constant but $$8$$ moles dissociate into atoms. Heat energy given to gas is 
  • $$4RT$$
  • $$6RT$$
  • $$3RT$$
  • $$5RT$$
A sample of gas in a box is at pressure $${ P }_{ 0 }$$ and temperature $${ T }_{ 0 }$$. If number of molecules is doubled and total kinetic energy of the gas kept constant then final temperature and pressure will be
  • $$T_{ 0 }\ .\ P_{ 0 }$$
  • $$T_{ 0 }\ .\ 2P_{ 0 }$$
  • $$\dfrac { { T }_{ 0 } }{ 2 } .{ 2P }_{ 0 }$$
  • $$\dfrac { { T }_{ 0 } }{ 2 } .{ P }_{ 0 }$$
The specific heat of a gas is found to be $$0.075$$ calories at constant volume and its formula $$wt$$ is $$40$$. The atomicity of the gas would be:
  • one
  • two
  • three
  • four
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 11 Engineering Physics Quiz Questions and Answers