Physics - Kinetic Theory of Gases
Exam Duration: 45 Mins Total Questions : 30
The average kinetic energy of a gas molecule at 270C is 6.2x10-21J.Its average kinetic energy at 1270C will be
- (a)
12.2x10-21J
- (b)
8.28x10-21J
- (c)
10.35x10-21J
- (d)
11.35x10-21J
Some gas at 300K is enclosed in a container.Now the container is placed on a fast moving jet.While the jet is in motion, the temperature of gas
- (a)
rises above 300K
- (b)
falls below 300K
- (c)
remains unchanged
- (d)
becomes unsteady
If one mole of a monoatomic gas \(\gamma={5\over3}\) is mixed with one mole of a diatomic gas\((\gamma={7\over5})\), the value of \(\gamma\) for mixture is
- (a)
1.40
- (b)
1.50
- (c)
1.53
- (d)
3.07
The root mean square velocity of gas molecules at 270 C is 1365 m/s.The gas is
- (a)
O2
- (b)
He
- (c)
N2
- (d)
CO2
Internal energy of n1 mole of hydrogen at temperature T is equal to internal energy of n2 mole of helium at temperature 2T.Then, ratio \(n_1\over n_2\)is
- (a)
\(3\over 2\)
- (b)
\(2\over3\)
- (c)
\(6\over5\)
- (d)
\(3\over7\)
If the masses of all molecules of a gas are halved and their speeds doubled, then the ratio of initial and final pressures would be
- (a)
2:1
- (b)
1 : 2
- (c)
4 : 1
- (d)
1 : 4
Two vessels having equal volume contain molecular hydrogen at one atmosphere and helium at two atmospheres respectively. If both samples are at the same temperature, the rms velocity of hydrogen molecules is:
- (a)
equal to that of helium
- (b)
equal to that of helium
- (c)
equal to that of helium
- (d)
\(\sqrt { 2 } \) times that of helium
In two vessels of same volume atomic hydrogen and helium at pressure of 1 atm and 2 atm are filled. If temperature of both the samples is same, then average speed of hydrogen atom (UH ) will be related to helium (UHe) as:
- (a)
\(\left< v_{ H } \right> =\sqrt { 2 } \left< v_{ He } \right> \)
- (b)
\(\left< v_{ H } \right> =\left< { v }_{ He } \right> \)
- (c)
\(\left< { v }_{ H } \right> =2\left< { v }_{ He } \right> \)
- (d)
\(\left< { v }_{ H } \right> =\left< { v }_{ He }/2 \right> \)
Two vessels A and B having equal volume contain equal Two vessels A and B having equal volume contain equal mark the correct statement.
- (a)
The pressure exerted by hydrogen is half that exerted by helium.
- (b)
The pressure exerted by hydrogen is half that exerted by helium.
- (c)
Average KE of the molecules of hydrogen is half the average KE of the molecules of helium.
- (d)
The pressure exerted by hydrogen is twice that exerted by helium.
The root mean square velocity of O2 at atmospheric pressure and at 0° C is:
- (a)
more than that of air
- (b)
less than that of ai
- (c)
equal to that of air
- (d)
nothing can be sa
N molecules, each of mass m, of gas A and 2N molecules, each of mass 2m, of gas B are contained in the same vessel which are maintained at a temperature T.The mean square of the velocity of molecules of B type is denoted by v2 and the mean square of the X component of the velocity of A type is denoted by w2 ; then w2/v2 is:
- (a)
2
- (b)
1
- (c)
(1/3.)
- (d)
(2/3)
A sample of gas is at 0° C to what temperature must it be raised in order to double the rms speed of its molecules?
- (a)
1030C
- (b)
2730C
- (c)
8190C
- (d)
10920C
The ratio of the total energy of all the molecules of one mole of O2 to the total energy of all the molecules of two moles of He at the same temperature is:
- (a)
2 : 1
- (b)
1 : 2
- (c)
5 : 4
- (d)
5 : 6
At constant temperature the value of Vrms will be same for which of the following?
- (a)
H2 and O2
- (b)
N2 and CO2
- (c)
Air and N2
- (d)
None of these
The gas in a vessel is subjected to a pressure of 20 atmosphere at a temperature 27° C. The pressure of the gas in the vessel after one half of the gas is released from the vessel and the temperature of the remainder is raised by, 50° C, is:
- (a)
8.5 atm
- (b)
10.8 atm
- (c)
11.67 atm
- (d)
17 atm
Two identical cylinders contain helium at 2.5 atmosphere and argon at one atmosphere respectively. If both the gases are filled in one of the cylinders. the pressure would be:
- (a)
3.5 atm
- (b)
1.75 atm
- (c)
1.50 atm
- (d)
1 atm
The relation between rms velocity , vrms and the most probable velocity , vrmp , of a gas is:
- (a)
vrms = vmp
- (b)
vrms = \(\sqrt { \frac { 3 }{ 2 } } \) vmp
- (c)
vrms = \(\sqrt { \frac { 2 }{ 3 } } \)vmp
- (d)
vrms =\(\frac { 2 }{ 3 } \)vmp
Consider I cc sample of air at absolute temperature To at sea level and another 1 cc sample of air at a height, where pressure is one-third atmosphere.The absolute temperature T of the sample at the height is:
- (a)
equal to (T0 / 3)
- (b)
equal to (3 / T0)
- (c)
equal to To
- (d)
cannot be determind in terms of T0 from the above data
The speeds of 5 molecules of a gas (in arbitrary units) are as follows 2, 3, 4, 5, 6 The root mean square speed for these molecules is:
- (a)
2.91
- (b)
4.00
- (c)
3.52
- (d)
4.24
Oxygen and hydrogen are at the same temperature T. The ratio of the mean kinetic energy of oxygen molecules to that of the hydrogen molecules will be:
- (a)
16:1
- (b)
1:1
- (c)
4:1
- (d)
1:4
IF both the temperature and the volume of an ideal gas are doubled , the pressure:
- (a)
Increases by a factor of 4
- (b)
is also doubled
- (c)
remains unchanged
- (d)
is diminshed by a factor \(\frac { 1 }{ 4 } \)
If VH, VN and VO denotes the root mean square velocities of molecules of hydrogen, notrogen and oxygen respectively at a given temperature then :
- (a)
VH > VN > VO
- (b)
VO > VN = VH
- (c)
VO > VH > VN
- (d)
VN > VO > VH
Two balloons are filled, one with pure He gas and other by air, respectively. If the pressure and temperature of these balloons are same, then the number of molecules per unit volume is:
- (a)
more in the He filled balloon
- (b)
same in both balloons
- (c)
more in air filled balloon
- (d)
in the ratio of I : 4
If the rms velocity ofagas is v, then:
- (a)
v2T = constant
- (b)
v2/T = constant
- (c)
vT2 = constant
- (d)
v is independent of T
If average velocity becomes 4 times then what will be the effect on rms velocity at that temperature?
- (a)
1.4 times
- (b)
4 times
- (c)
2 times
- (d)
\(\frac { 1 }{ 4 } \) times
The ratio of the vapour densities of two gases at a given temperature is 9 : 8 .The ratio of the rms velocities of their molecules is :
- (a)
3 : 2\(\sqrt { 2 } \)
- (b)
2\(\sqrt { 2 } \) : 3
- (c)
9 : 8
- (d)
8 : 9