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

The  maximum speed of the molecules of a gas in a vessel is $$400\ m/s$$. If half of the gas leaks out, at constant temperature, the $$rms$$ speed of the remaining molecules will be-
  • $$800\ m/s$$
  • $$400\sqrt2\ m/s$$
  • $$400\ m/s$$
  • $$200\ m/s$$
Internal energy of $$n_{1}$$ moles of hydrogen at temperature $$150\ K$$ is equal to the internal energy of $$n_{2}$$ moles of helium at temperature $$300\ K$$. The ratio of $$n_{1}/n_{2}$$ is
  • $$3:5$$
  • $$2:3$$
  • $$6:5$$
  • $$5:6$$
Heat is added to an ideal gas, and the gas expands. In such a process the temperature 
  • must always increase
  • will remain the same if the work done equals the heat added
  • must always decrease
  • will remains the same If change in internal energy equals the heat added.
If number of molecules of $${ H }_{ 2 }$$ are doubles  than that of $${ O }_{ 2 }$$, then ratio of kinetic energy of hydrogen to that of oxygen at 300 K is 
  • 1.1
  • 1.2
  • 2.1
  • 1.16
On increasing temperature of the reacting system by $$10$$ degrees the rate of reaction almost doubles. The most appropriate reason for this is
  • collision frequency increases
  • activation energy decreases by increases in temperatuer
  • the fraction of molecules having energy equal to threshold energy or more increase
  • the value of threshold energy decreases
Two spherical vessel of equal volumes, are connected by a narrow tube. The apparatus contains an ideal gas at one atmosphere and 300K. Now if one vessel is immersed in a bath of constant temperature 600 K and the other in a bath of constant temperature 300 K. Then the common pressure will be
1239841_9b0d4ab4a8f6437fb5d9ece4c50af84e.png
  • $$1 atm$$
  • $$4/5 atm$$
  • $$4/3 atm$$
  • $$3/4 atm$$
Select the correct statement
  • The average KE of an ideal gas in calories per mole is approximately equal to its absolute temperature
  • The average KE of an ideal gas in calories per mole is approximately equal to two times its absolute temperature
  • The average KE of an ideal gas in calories per mole is approximately equal to three times its absolute temperature
  • The average KE of an ideal gas in calories per mole is approximately equal to 1.5 times its absolute temperature
n moles of an ideal monoatomic gas undergoes an isothermal expansion at temperature T during which its volume becomes 4 times. The work done on the gas and change in internal energy of the gas respectively is
  • n RT Ln 4,0
  • - n RT Ln 4,0
  • n RT Ln 4 $$\frac { 3 n R T } { 2 }$$
  • - n RT Ln 4, $$\frac { 3 n R T } { 2 }$$
Air is filled at $$60^0$$C in a vessel of open mouth. The vessel is heated to a temperature T so that $$1/4^{th}$$ part of air escapes. The value of T is : 
  • $$80^0$$C
  • $$444^0$$C
  • $$333^0$$C
  • $$171^0$$C
The magnetic monment of a diamagnetic atom is 
  • Much greater than one
  • 1
  • Between zero and one
  • Equal to zero
$$'n'$$ moles of an ideal gas undergoes a process $$A\rightarrow B$$ as shown in the figure. The maximum temperature of the gas during the process will be :
1253751_287b71a57bbe47b19501c99d9202016b.png
  • $$\cfrac{3P_{0}V_{0}}{2nR}$$
  • $$\cfrac{9P_{0}V_{0}}{2nR}$$
  • $$\cfrac{9P_{0}V_{0}}{nR}$$
  • $$\cfrac{9P_{0}V_{0}}{4nR}$$
Find the approximate number of molecules contained in a vessel of volume $$7$$ litres at $$0^oC$$ at $$1.3\times 10^5$$ pascals:
  • $$2.4\times 10^{23}$$
  • $$1.5\times 10^{24}$$
  • $$6\times 10^{23}$$
  • $$4.8\times 10^{23}$$
Where temperature of a gas, contained in closed vessel is increased by $$5C$$, its pressure increases by $$1%$$.The original temperature of the gas was approx i - mately:- 
  • $$500C$$
  • $$273C$$
  • $$227C$$
  • $$50C$$
A rigid container of negligible heat capacity contains one mole of an ideal gas. The temperature of the gas increase by $$1^{o}C$$ if $$3 \cdot 0\ cal$$ of heat is added to it. The gas may be
  • helium
  • argon
  • oxygen
  • carbon dioxide
An ant is walking on the horizontal surface. The number of degree of freedom of ant will be
  • $$1$$
  • $$2$$
  • $$3$$
  • $$6$$
The mass of hydrogen molecules is $$3.32 \times 10 ^ { - 24 }$$ gm. If $$10 ^ { 23 } \mathrm { H } _ { 2 }$$ molecules strike $$2$$ sq. cm are per second with velocity of $$10 ^ { 5 }$$ cm/sec at an angle of $$45 ^ { \circ }$$ to the normal to wall, then the exerted pressure will be 
  • $$2.35 \mathrm { N } / \mathrm { m } ^ { 2 }$$
  • $$23.5 \mathrm { N } / \mathrm { m } ^ { 2 }$$
  • $$235 \mathrm { N } / \mathrm { m } ^ { 2 }$$
  • $$2350 \mathrm { N } / \mathrm { m } ^ { 2 }$$
Which of the following is incorrect relation fot a perfect gas?
  • $${ \quad \left( \frac { \eth U }{ \eth V } \right) }_{ T }=0$$
  • $${ \quad \left( \frac { \eth H }{ \eth P } \right) }_{ T }=0$$
  • $${ \quad \left( \frac { \eth T }{ \eth P } \right) }_{ H }=0$$
  • $${ \quad \left( \frac { \eth U }{ \eth T } \right) }_{ V }=0$$
If the law of equipartition of energy is applied to solid elements like silver, the heat capacity of one gram atom of the solid is
  • $$\dfrac5 2 R$$
  • $$\dfrac32 R$$
  • $$R$$
  • $$3 R$$
When a monoatomic gas expands at consatnt pressure, the percentage of heat supplied that increases temperature of the gas and in doing external work in expansion at constant pressure is
  • $$100%,0$$
  • $$60%,40%$$
  • $$40%,60%$$
  • $$75%,25%$$
An ideal gas is expanding such that $$PT = constant$$. The coefficient of volume expansion of the gas is
  • $$\dfrac {1}{T}$$
  • $$\dfrac {2}{T}$$
  • $$\dfrac {3}{T}$$
  • $$\dfrac {4}{T}$$
The Kinetic energy of translation of $$20$$ gram of  oxygen at $${47^0}C$$ is [ Molecular weight of $${O_2} = 32$$ gram/ mol and $$R = 8.3J/mol/K$$]
  • 2490 ergs
  • 2490 J
  • 249 J
  • 960 J
Two kg of a monoatomic gas is at a pressure of $$4 \times 10^4 N/m^2$$ . The density of the gas is $$8 kg /m^3$$. What is the order of energy of the gas due to its thermal motion ?
  • $$10^3 J$$
  • $$10^5 J$$
  • $$10^6 J$$
  • $$10^4 J$$
 The kinetic energy of 1 gram mole of a gas at normal temperature and pressure is ( R = 8.31 J/mole- K)
  • 0.56 $$\times { 10 }^{ 4 }J$$
  • 1.3 $$\times { 10 }^{ 2 }J$$
  • 2.7 $$\times { 10 }^{ 2 }J$$
  • 3.4 $$\times { 10 }^{ 3 }J$$
One $$kg$$ of diatomic gas is at a pressure of $$8\times 10^{4}\ N/m^{2}$$. The density of the gas is $$4\ kg/m^{3}$$. What is the energy of the gas due to its thermal motion?
  • $$5\times 10^{4} J$$
  • $$6\times 10^{4} J$$
  • $$7\times 10^{4} J$$
  • $$3\times 10^{4} J$$
For ideal monoatomic gas,the universal gas constant R is n times molar heat capacity at constant pressure $$ C_p $$ Here n is :-
  • 0.67
  • 1.4
  • 0.4
  • 1.67
A mixture Of $$n _ { 2 }$$ moles of mono atomic gas and $$n _ { 2 }$$ moles of diatomic gas has $$\frac { C _ { p } } { C _ { V } } = y = 1.5$$
  • $$n _ { 1 } = n _ { 2 }$$
  • $$2 n _ { 1 } = n _ { 2 }$$
  • $$n _ { 1 } = 2 n _ { 2 }$$
  • $$2 n _ { 1 } = 3 n _ { 2 }$$
 An ideal gas at pressure P is adiabatically compressed so that its density becomes n times the initial value. The final pressure of the gas will be $$ ( \gamma= C_p/C_v) $$ 
  • $$ n^\gamma P $$
  • $$ n^{-\gamma} P $$
  • $$ n^{\gamma-1} P $$
  • $$ n^{1-\gamma} P $$
The gas mixture constists of $$3$$ moles of oxygen and $$5$$ moles of argon at temperature $$T$$. Considering only translational and rotational modes, the total internal energy of the system is:
  • $$12\ RT$$
  • $$20\ RT$$
  • $$15\ RT$$
  • $$4\ RT$$
The volume of an ideal gas is 1 litre and its pressure is equal to 72 cm of mercury column. The volume of gas is made $$ 900 cm^3 $$ by compressing it isothermally. The stress of the gas will be 
  • 8 cm (mercury)
  • 7 cm (mercury)
  • 6 cm (mercury)
  • 4 cm (mercury)
Two moles of helium gas are taken along the path ABCD (as shown in figure). The work done by the gas is
1326367_8c87ce061a7f4477b49097729314934c.PNG
  • $$2000R(1 + ln \frac{4}{3})$$
  • $$500R(3+ln4)$$
  • $$500R(2+ln\frac{16}{9})$$
  • $$1000R(1+ln\frac{16}{9})$$
What is the mass of :
  • $$0.2$$ mole of oxygen atoms?
  • $$0.5$$ mole of water molecules?
  • Both a and b
  • None of these
An open container is placed in atmosphere. During a time interval, temperature of atmosphere increases and then decreases. The internal energy of gas in container
  • First increases then decreases because internal energy depends upon temperature
  • First decreases then increases
  • Remains constant
  • Is inversely proportional to temperature
Half mole of an ideal monoatomic gas is heated at constant  pressure of 1 atm from $${ 20 }^{ 0 }C$$ to $${ 90 }^{ 0 }C$$ . Work done by gas is close to : ( gas constant R=8.31 j / mol -k ) 
  • 146 j
  • 581 j
  • 73 j
  • 291 j
The mean free path of nitrogen molecules at a pressure of 1.0 atm and temperature $$ 0^0 C $$ is $$ 0.8 \times  10^{-7} m $$. If the number of density of molecules is $$ 2.7 \times 10^{25} $$ per $$ m^3 $$, then the molecular diameter is 
  • $$0.32 nm$$
  • $$ 3.2 A^0 $$
  • $$ 3.2 \mu m $$
  • $$2.3 mm$$
One mole of an ideal gas expands against a constant external pressure of 1 atm from a volume of $$10d{ m }^{ 3 }$$ to a volume of $$30d{ m }^{ 3 }$$. What would be the work done in joules?
  • $$-2026 J$$
  • $$+2026 J$$
  • $$-1947 J$$
  • $$1648 J$$
The temperature at which the rms of a hydrogen molecule is equal to that of an oxygen molecule at $$47^{\circ}C$$  is  
  • -253 K
  • -73 K
  • 3 K
  • 20 K
A sample of gas is at $$0^{\circ}C$$. To what temperature must it be raised in order to double the rms speed of its molecules?
  • $$102^{\circ}C$$
  • $$273^{\circ}C$$
  • $$819^{\circ}C$$
  • $$1092^{\circ}C$$
Which of the following statements about kinetic theory of gases is wrong
  • The molecules of a gas are in continuous random motion
  • The molecules continuously undergo inelestic collisions
  • The molecules do not interact with each other excepted during collisions
  • The collisions among the molecules are of short duration
N moles of a monoatomic gas is carried round the reversible rectangular cycle ABCDA as shown in the diagram. The temperature at $$A$$ is $$T _ { 0 }$$ . The thermodynamic efficiency of the cycle is


1372128_34b8ce5be7e548d7bf2db455e8faee63.jpg
  • $$ 15 \%$$
  • $$ 50 \%$$
  • $$ 20 \%$$
  • $$ 25 \%$$
Find the amount of work done to increase the temperature of 1 mol of an ideal gas by $$30 ^ { \circ } { C }$$ if it is expanding under the condition $$V \propto T ^ { 2 / 3 }$$ .
  • $$166.2$$ $${ J }$$
  • $$136.2$$ $${ J }$$
  • $$126.2$$ $${ J }$$
  • None of these
The pressure in the tyre of a car is four times the atmospheric pressure at $$300\, K$$. If this tyre suddenly bursts, its new temperature will be $$(\gamma = 1.4)$$
  • $$300(4)^{1.4/0.4}$$
  • $$300\,\left(\dfrac{1}{4}\right)^{-0.4/1.4}$$
  • $$300(2)^{-0.4/1.4}$$
  • $$300(4)^{-0.4/1.4}$$
Average kinetic energy per mole if an monoatomic ideal gas at 
  • $$5.8\times { 10 }^{ -2 }\quad J$$
  • $$9.5\times { 10 }^{ -2 }\quad J$$
  • $$5.6\times { 10 }^{ -2 }\quad J$$
  • $$12.47 J$$
The specific heat of a monatomic gas at constant volume is $$0.075 kcal$$ $$  k g^{-1} K^{-1} .  $$ Its atomic weight will be
  • $$10$$
  • $$30$$
  • $$40$$
  • $$90$$
A vessel contains 3.20 g of oxygen and $$2.80 g$$ of nitrogen. The vessel is moving with a velocity $$100 \mathrm { m } / \mathrm { s }$$ . The vessel is suddenly stopped. Find the change in temperature -
  • $$7.2 ^ { \circ } \mathrm { C }$$
  • $$6.0 ^ { \circ } \mathrm { C }$$
  • $$8.3 ^ { \circ } \mathrm { C }$$
  • $$6.5 ^ { \circ } \mathrm { C }$$
The mass of litre of dry air at N.T.P is 1.293 g . Find the mass of 3 litres of air at $$117^oC$$ and a pressure of 4 atmospheres _____.
  • 10.86 g
  • 5.6 g
  • 6.4 g
  • 7.2 g
The specific heat of a substance is $$0.09 cal/gm^oC$$. If the temperature is measured on Pahrenhelt scale the value of its specific heat in $$cal/gm/^oF$$ is _________.
  • 0.05
  • 0.9
  • 0.005
  • 0.5
Heat capacity at constant temperature and constant pressure for $${ H }_{ 2 }$$ is :-
  • 5 cal $${ moI }^{ -1 }{ K }^{ -1 }$$
  • 7 cal $${ moI }^{ -1 }{ K }^{ -1 }$$
  • 8 cal $${ moI }^{ -1 }{ K }^{ -1 }$$
  • $$\infty $$
If the temperature of the gas becomes three times the initial absolute temperature, speed of the gas molecules
  • Becomes $$\dfrac{1}{ 3}$$ times the initial ms speed
  • Becomes $$\dfrac{1}{\sqrt { 3 }}$$ times the initial rms speed
  • Becomes $$\sqrt { 3 }$$ times times the initial ms speed
  • Becomes 3 times the initial rms speed
The temperature of a gas is $$-{ 68 }^{ \circ  }C$$ At what temperature will the average kinetic energy of its molecules be twice that of $$-{ 68 }^{ \circ  }C$$ ?
  • $$137^{ \circ }C$$
  • $$127^{ \circ }C$$
  • $$100^{ \circ }C$$
  • $$105^{ \circ }C$$
An ideal gas is expanding such that $$P T ^ { 2 } =$$ constant. The coefficient of volume expansion of the gas is
  • $$\dfrac{1}{T}$$
  • $$\dfrac{2}{T}$$
  • $$\dfrac{3}{T}$$
  • $$\dfrac{4}{T}$$
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