A gas mixture consists of molecules of type 1, 2 and 3, with molar masses m1>m2>m3. Vrms and K¯ are the r.m.s. speed and average kinetic energy of the gases. Which of the following is true

  •  Vrms1<Vrms2<Vrms3 and K¯1=K¯2=K¯3

  •  Vrms1=Vrms2=Vrms3 and K¯1=K¯2>K¯3

  •  Vrms1>Vrms2>Vrms3 and K¯1<K¯2>K¯3

  •  Vrms1>Vrms2>Vrms3 and K¯1<K¯2<K¯3

Two ideal gases at absolute temperature T1 and T2 are mixed. There is no loss of energy. The masses of the molecules are m1 and m2 and the number of molecules in the gases are n1 and n2 respectively. The temperature of mixture will be

  •  T1+T22 energy                     

  •  T1+T2n1n2

  •  n1T1+n2T2n1+n2                         

  •  T1+T2

The molecules of an ideal gas at a certain temperature have

  • Only potential energy

  • Only kinetic energy

  • Potential and kinetic energy both

  • None of the above

The temperature at which the average translational kinetic energy of a molecule is equal to the energy gained by an electron in accelerating from rest through a potential difference of 1 volt is

  •   4.6×103 K                 

  •   11.6×103 K

  •   23.2×103 K               

  •   7.7×103 K

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 at temperature T. The mean square of the velocity of molecules of gas B is v2 and the mean square of x component of the velocity of molecules of gas A is w2. The ratio is w2v2is

  •   1                                 

  •   2

  •   13                               

  •   23

A gas is filled in a cylinder, its temperature is increased by 20% on Kelvin scale and volume is reduced by 10%. How much percentage of the gas will leak out: (Assume pressure is constant)

  • 30%                           

  • 40%

  • 15%                           

  • 25%

The air density at Mount Everest is less than that at the sea level. It is found by mountaineers that for one trip lasting a few hours, the extra oxygen needed by them corresponds to 30,000 cc at sea level (pressure 1 atmosphere, temperature 27°C). Assuming that the temperature around Mount Everest is –73°C and that the oxygen cylinder has capacity of 5.2 litre, the pressure at which O2 be filled (at site) in cylinder is

  •   3.86 atm                     

  •   5.00 atm

  •   5.77 atm                     

  •   1 atm

12 mole of helium gas is contained in a container at S.T.P. The heat energy needed to double the pressure of the gas, keeping the volume constant (specific heat of the gas =3 J gm-1 K-1) is 

  •   3276 J                   

  •   1638 J

  •   819 J                     

  •   409.5 J

The equation of state of a gas is given by P+aT2VVc=RT+b, where a, b, c and R are constants. The isotherms can be represented by P=AVm-BVn, where A and B depend only on temperature and 

  •  m=-c and n=-1                       

  •  m=c and n=1

  •  m=-c and n=1                           

  •  m=c and n=-1

70 calories of heat is required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30°C to 35°C. The amount of heat required to raise the temperature of same gas through the same range (30°C to 35°C) at constant volume (R = 2 cal/mol/K)

  •   30 cal                       

  •   50 cal

  •   70 cal                       

  •   90 cal

A closed compartment containing gas is moving with some acceleration in horizontal direction. Neglect effect of gravity. Then the pressure in the compartment is

  • Same everywhere                           

  • Lower in the front side

  • Lower in the rear side                     

  • Lower in the upper side

Three closed vessels A, B and C are at the same temperature T and contain gases which obey the Maxwellian distribution of velocities. Vessel A contains only O2 , B only N2 and C a mixture of equal quantities of O2 and N2. If the average speed of the O2 molecules in vessel A is V1 , that of the N2 molecules in vessel B is V2 , the average speed of the O2 molecules in vessel C is

  •  V1+V2/2                           

  •  V1

  •  V1V21/2                               

  •  3 kT/M

A box containing N molecules of a perfect gas at temperature T1 and pressure P1. The number of molecules in the box is doubled keeping the total kinetic energy of the gas same as before. If the new pressure is P2 and temperature T2, then

  •  P2=P1, T2=T1                           

  •  P2=P1, T2=T12

  •  P2=2P1, T2=T1                         

  •  P2=2P1, T2=T12

Two identical glass bulbs are interconnected by a thin glass tube. A gas is filled in these bulbs at N.T.P. If one bulb is placed in ice and another bulb is placed in hot bath, then the pressure of the gas becomes 1.5 times. The temperature of hot bath will be

      

  •   100°C                     

  •   182°C

  •   256°C                     

  •   546°C

Two containers of equal volumes contain the same gas at pressures P1 and P2 and absolute temperatures T1 and T2, respectively. On joining the vessels, the gas reaches a common pressure P and common temperature T. The ratio P/T is equal to

  •  P1T1+P2T2                           

  •  P1T1+P2T2T1+T22

  •  P1T2+P2T1T1+T22                     

  •  P12T1+P22T2

Which one, of the following, graphs represents the behaviour of an ideal gas at constant temperature?

  •  

  •                             

  •                             

  •  

A closed vessel contains 8gm of oxygen and 7gm of nitrogen. The total pressure is 10 atm at a given temperature. If now oxygen is absorbed by introducing a suitable absorbent the pressure of the remaining gas in atm will be

  •   2                               

  •   10

  •   4                               

  •   5

CO2O=C=O is a triatomic gas. Mean kinetic energy of one gram gas will be (If N-Avogadro's number, k-Boltzmann's constant and molecular weight of CO2=44 , Degree of freedom f = 7)

  •  3/88 NkT                             

  •  5/88 NkT

  •  6/88 NkT                             

  •  7/88 NkT

40 calories of heat is needed to raise the temperature of 1 mole of an ideal monoatomic gas from 20°C to 30°C at a constant pressure. The amount of heat required to raise its temperature over the same interval at a constant volume R=2 calorie mole-1 K-1 is

  •   20 calorie                   

  •   40 calorie

  •   60 calorie                   

  •   80 calorie

The pressure and volume of saturated water vapour are P and V respectively. It is compressed isothermally thereby volume becomes V/2, the final pressure will be

  •   More than 2P                         

  •   P

  •   2P                                         

  •   4P

If the intermolecular forces vanish away, the volume occupied by the molecules contained in 4.5 kg water at standard temperature and pressure will be

  •   5.6 m3                             

  •   4.5 m3

  •   11.2 litre                           

  •   11.2 m3

When an air bubble of radius ‘r’ rises from the bottom to the surface of a lake, its radius becomes 5r/4 (the pressure of the atmosphere is equal to the 10 m height of water column). If the temperature is constant and the surface tension is neglected, the depth of the lake is

  •   3.53 m                   

  •   6.53 m

  •   9.53 m                   

  •   12.53 m

A horizontal uniform glass tube of 100 cm, length sealed at both ends contain 10 cm mercury column in the middle. The temperature and pressure of air on either side of mercury column are respectively 81°C and 76 cm of mercury. If the air column at one end is kept at 0°C and the other end at 273°C, the pressure of air which is at 0°C is (in cm of Hg)

  •   76                                   

  •   68.2

  •   87.9                            

  •   122

At standard temperature and pressure the density of a gas is 1.3 kg/m3 and the speed of the sound in gas is 330 m/sec. Then the degree of freedom of the gas will be

  •   3                         

  •   4

  •   5                         

  •   6

The temperature of 5 moles of a gas which was held at constant volume was changed from 100°C to 120°C. The change in internal energy was found to be 80 Joules. The total heat capacity of the gas at constant volume will be equal to

  •   8 J/K                     

  •   0.8 J/K

  •   4.0 J/K                 

  •   0.4 J/K

The temperature at which the r.m.s. speed of hydrogen molecules is equal to escape velocity on earth surface, will be

  •   1060 K                   

  •   5030 K

  •   8270 K                   

  •   10063 K

Inside a cylinder having insulating walls and closed at ends is a movable piston, which divides the cylinder into two compartments. On one side of the piston is a mass m of a gas and on the other side a mass 2 m of the same gas. What fraction of volume of the cylinder will be occupied by the larger mass of the gas when the piston is in equilibrium ? Consider that the movable piston is conducting so that the temperature is the same throughout

  •   14                                 

  •   13

  •   12                                 

  •   23

The diameter of oxygen molecules is 2.94×10-10 m. The Vander Waal's gas constant 'b' in m3/mol will be

  •   3.2                             

  •   16

  •   32×10-4                 

  •   32×10-6

The temperature of the mixture of one mole of helium and one mole of hydrogen is increased from 0°C to 100°C at constant pressure. The amount of heat delivered will be

  •   600 cal                   

  •   1200 cal

  •   1800 cal                 

  •   3600 cal

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 O2 molecule to that per N2 molecule is

  •   1 : 1

  •   1 : 2

  •   2 : 1

  •   Depends on the moments of inertia of the two molecules

0:0:1


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