#### 11th Standard Physics Kinetic Theory of Gases English Medium Free Online Test One Mark Questions 2020 - 2021

11th Standard

Reg.No. :
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Physics

Time : 00:20:00 Hrs
Total Marks : 20

20 x 1 = 20
1. An ideal gas is maintained at constant pressure. If the temperature of an ideal gas increases from 100K to 1000K then the rms speed of the gas molecules

(a)

increases by 5 times

(b)

increases by 10 times

(c)

remains same

(d)

increases by 7 times

2. The average translational kinetic energy of gas molecules depends on

(a)

number of moles and T

(b)

only on T

(c)

P and T

(d)

P only

3. The ratio $\gamma =\frac { { C }_{ p } }{ { C }_{ V } }$ for a gas mixture consisting of 8 g of helium and 16 g of oxygen is

(a)

23/15

(b)

15/23

(c)

27/11

(d)

17/27

4. If the temperature and pressure of a gas is doubled the mean free path of the gas molecules

(a)

remains same

(b)

doubled

(c)

tripled

(d)

5. A sample of gas consists of $\mu$1 moles of monoatomic molecules, $\mu$2 moles of diatomic molecules and $\mu$3 moles of linear triatomic molecules. The gas is kept at high temperature. What is the total number of degrees of freedom?

(a)

[3$\mu$1 + 7( $\mu$2 + $\mu$3)] NA

(b)

[3$\mu$1 + 7$\mu$2 + 6$\mu$3] NA

(c)

[7$\mu$1 + 3( $\mu$2 + $\mu$3)] NA

(d)

[3$\mu$1 + 6( $\mu$2 + $\mu$3)] NA

6. Which of the following gases will have least rms speed at a given temperature?

(a)

Hydrogen

(b)

Nitrogen

(c)

Oxygen

(d)

Carbon dioxide

7. The perfect gas equation can be written as

(a)

PV = $\mu$RT

(b)

PV = $\mu$R

(c)

PV = RT

(d)

P = $\mu$RTV

8. If there are n no. of molecules per unit volume and m is the mass of each, Vx is the x - component of velocity pressure can be written as,

(a)

P= nm${ V }_{ x }^{ 2 }$

(b)

P= 2nm${ V }_{ x }^{ 2 }$

(c)

P= m${ V }_{ x }^{ 2 }$

(d)

P= n${ V }_{ x }^{ 2 }$

9. During an adiabatic process, the pressure of a gas is found to be proportional to the cube of its absolute temperature the ratio $\frac { { C }_{ p } }{ { C }_{ v } }$for the gas is

(a)

$\frac{4}{3}$

(b)

2

(c)

$\frac{5}{3}$

(d)

$\frac{3}{2}$

10. The ratio of the vapour densities of two gases at a gn is 9 : 8. Theratio of the rms velocity of their molecules is

(a)

3: 2$\sqrt{2}$

(b)

2$\sqrt{2}$:3

(c)

9:8

(d)

8:9

11. The temperature is changed from 27°C to 327°C. Find ratio of K.E of molecules at two temperature.

(a)

3:2

(b)

2:3

(c)

1:2

(d)

2:1

12. Oxygen and hydrogen gases are at the same temperature the ratio of the average K.E of an oxygen molecule and that of a hydrogen molecule is

(a)

16

(b)

4

(c)

1

(d)

$\frac{1}{4}$

13. Pressure exerted by a perfect gas is equal to

(a)

mean K.E. per unit volume

(b)

half of mean K.E. per unit volume

(c)

one-third of mean K.E. per unit volume

(d)

two-third of mean K.E. per unit volume.

14. Two gases are enclosed in a container at constant temperature. One of the gases, which is diatomic, has relative molecular mass eight times the other, which is monoatomic. The ratio of the rms speed of the molecules of the monoatomic gas to that of the molecules of the diatomic gas is ________

(a)

8

(b)

4

(c)

2$\sqrt2$

(d)

2

15. At a given temperature which of the following gases possesses maximum rms velocity of molecules?

(a)

H2

(b)

O2

(c)

N2

(d)

CO2

16. A gas is enclosed in a container which is then placed on a fast moving train. The temperature of the gas  ________.

(a)

rises

(b)

remains unchanged

(c)

falls

(d)

17. Ajar has mixture of hydrogen and Oxygen gases in the ratio 1 : 5. The ratio of mean kinetic energies of hydrogen and Oxygen molecules is ________.

(a)

1: 5

(b)

5: 1

(c)

1: 1

(d)

1: 25

18. Pressure exerted by a gas is _______.

(a)

independent of the density of the gas

(b)

inversely proportional to the density of the gas

(c)

directly proportional to the density of the gas

(d)

directly proportional to the square of the density of the gas

19. A real gas behaves as an ideal gas at _________.

(a)

low pressure and high temperature

(b)

high pressure and low temperature

(c)

low pressure and low temperature

(d)

high pressure and high temperature.

20. Two different ideal gases are enclosed in two different vessels at the same pressure. If $\rho$1 and $\rho$2 are their densities and v1 and v2 their rrns speeds, respectively then - is equal to ________.

(a)

$\frac { { \rho }_{ 1 }^{ 2 } }{ { \rho }_{ 2 }^{ 2 } } \\$

(b)

$\frac { { \rho }_{ 2 }^{ 2 } }{ { \rho }_{ 1}^{ 2 } } \\$

(c)

$\sqrt { \frac { { \rho }_{ 1 }^{ } }{ { \rho }_{ 2 }^{ } } }$

(d)

$\sqrt { \frac { { \rho }_{ 2 }^{ } }{ { \rho }_{ 1 }^{ } } }$