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CBSE Questions for Class 11 Engineering Physics Kinetic Theory Quiz 10 - MCQExams.com

Mean kinetic energy(or average energy) per gm molecule of a monoatomic gas is given by:
  • 3RT/2
  • kT/2
  • RT/2
  • 3kT/2
The de-Broglie wavelength of a particle accelerated with 150 volt potential is 1010 m. If it accelerated by 600 volts p.d. its wavelength will be
  • 0.25 Ao
  • 0.5 Ao
  • 1.5 Ao
  • 2 Ao
We have a jar A filled with gas characterized by parameters P, V and T and another jar B filed with gas with parameters 2P, Vl4 and 2T, where the symbols have their usual meanings. The ratio of the number of molecules of jar A to those of jar B is 
  • 1 : 1
  • 1 : 2
  • 2 : 1
  • 4 : 1
If E is the heat of reaction for C2H3OH(1)+3O2(g)2CO2(s)+3H20(1) at constant volume, the H ( Heat of reaction at constant pressure) at constant temperature is:
  • H=E+2RT
  • H=E2RT
  • H=E+RT
  • H=ERT
At what temperature does the average translational kinetic energy of a molecule in a gas become equal to kinetic energy of an electron accelerated from rest through a potential difference of 1 volt?(k=1.38×1023 J/k)
  • 3770K
  • 7370K
  • 7730K
  • 7330K
The total kinetic energy of 1 mole of N2 at 27C will be approximately
  • 3739.662 J 
  • 1500 calorie
  • 1500 kilo calorie
  • 1500 erg.
Three perfect gasses at absolute temperatures T1, T2 and T3 are mixed. If number of molecules of the gasses are n1, n2 and n3 respectively then temperature of mixture will be (assume no loss of energy)
  • T1+T2+T33
  • n21T1+n22T2+n23T3n1+n2+n3
  • n1T1+n2T2+n3T3n1+n2+n3
  • T1+T2+T3n1+n2+n3
Calculate γ (ratio of Cp and Cv ) for triatomic linear gas at high temperature. Assume that the contribution of the vibrational degree of freedom is 75%?
  • 1.222
  • 1.121
  • 1.18
  • 1.33
A vessel has 6g of oxegen at pressure P and temperature 400 K. A small hole is made in it so that oxygen leaks out. How much oxygen leaks out if the final pressure is P/2 and temperature is 300 K
  • 3g
  • 2g
  • 4g
  • 5g
A gas undergoes a process such that P1T. If the molar heat capacity for this process is 24.93J/molK, then what is the degree of freedom of the molecules of the gas?
  • 8
  • 4
  • 2
  • 6
The degrees of freedom of a triatomic gas is? (consider moderate temperature)
  • 6
  • 4
  • 2
  • 8
Change in momentum of the gas molecules as they strike the walls
One mole of an ideal gas (mono-atomic) at temperature T0 expands slowly according to law P2=cT (c is constant). If final temperature is 2T0, heat supplied to gas is
  • 2RT0
  • 32RT0
  • RT0
  • RT02
Which graph shows how the average kinetic energy of the particles varies with absolute temperature for an ideal gas?
The effect of temperature on Maxwell's speed distribution is correctly shown by 
Select the incorrect relation. (Where symbols have their usual meanings)
  • Cp=γRγ1
  • CpCv=R
  • ΔU=PfVfPiVi1γ
  • Cv=Rγ1
The ratio of adiabatic to isothermal elasticity of  diatomic gas is:-
  • 1.67
  • 1.4
  • 1.33
  • 1.27
A vessel contains 28 gm of N2 and 32 gm of O2 at temperature T = 1800 K and pressure 2 atm pressure it N2 dissociates 30 and O2 dissociates 50 if temperature remains constant. 
  • 2 atm
  • 1 atm
  • 2.8 atm
  • 1.4 atm
An ideal gas has an initial volume V and pressure P. In doubling its volume the minimum work done will be in (of the given processes):
  • Isobaric process
  • Isothermal process
  • Adiabatic process
  • Same in all given processes
The velocities of sound in an ideal gas at temperature T1 and T2k are found to be V1 and V2 respectively.If the r.m.s. velocities of the molecules of the same gas at the same temperatures T1 and T2 are v1 and v2 respectively then
  • v2=v1(V1V2)
  • v2=v1(V2V1)
  • v2=v1V2V1
  • v2=v1V1V2
For gas, if the ratio of specific heats at constants pressure P and constant volume V is γ, then the value of degree of freedom is:
  • γ+1γ1
  • γ1γ+1
  • 12(γ1)
  • 2γ1
A vessel contains a non-linear triatomic gas. If 50% of gas dissociate into individual atom, then find new value of degree of freedom by ignoring the vibrational mode and any further dissociation 
  • 2.15
  • 3.75
  • 5.25
  • 6.35
At which of the following temperature would the molecules of a gas have twice the average kinetic energy they have at 20oC
  • 40oC
  • 80oC
  • 313oC
  • 586oC
The lowest pressure(the best Vaccum) that can be created in laboratory at 27 degree is 1011 mm of Hg. At this pressure, the number of ideal gass molecules per cm3 will be
  • 3.22×1012
  • 1.61×1012
  • 3.21×106
  • 3.22×105
The internal energy of an ideal gas increases during an isothermal process when the gas is 
  • Expanded by adding more molecules to it
  • Expanded by adding more heat to it
  • Expanded against zero pressure
  • Compressed by doing work on it
One-gram mole of nitrogen occupies 2×104 cc at a pressure of 106dynes/cm2. The average energy of a nitrogen molecule (in erg) will be:(Avogadrosnumber=6×1025)
  • 14×1013
  • 10×1012
  • 106
  • 2×106
The molecules of a given mass of gas have rms velocity 200 ms1 at 27C and 105 Nm2 pressure. When the absolute temperature is doubled and the pressure is halved, the rms speed of the molecules of the same gas is:
  • 200 ms1
  • 400 ms1
  • 2002 ms1
  • 4002 ms1
In a thermodynamic system, working substance is ideal gas, its internal energy is in the form of  
  •  kinetic energy
  •  kinetic and potential energy
  •  potential energy
  •  None of the above
T1 is the temperature of oxygen enclosed in a cylinder. The temperature is increased to T2 and Maxwellan distribution curves for O2 at temperature T1 and T2 are plotted. If A1 and A2 are the areas under the curves and the speed axis, in both cases , then 
  • A1>A2
  • A1<A2
  • A_1 = A_2$$
  • A1=A2
Molar heat capacity of water in equilibrium with ice at constant pressure is 
  • Zero
  • 40.45 kJ K1mol1
  • 75.48 JK1mol1
The speed of a longitudinal wave in a mixture containing 4 moles of He and 1 mole of Ne at 300 K will be
  • 930 m/s
  • 541 m/s
  • 498 m/s
  • None of these
In a process the pressure of gas is inversely proportional to the square of volume If temperature of the gas is increased then work done by the gas
  • Is positive
  • Is negative
  • Is zero
  • May be positive
Hydrogen is a diatomic gas. Its molar specific heat at constant volume is very nearly
  • 3R2
  • 5R2
  • 7R2
  • (b) or (c) depending on the temperature.
In a thermodynamic system, working substance is ideal gas, its internal energy is in the form of
  • Kinetic energy
  • Kinetic and potential energy
  • Potential energy
  • None of the above
In a diatomic molecule, the rotational energy at a given temperature
  • obeys Maxwell's distribution.
  • have the same value for all molecules.
  • equals the translational kinetic energy for each molecule.
  • is (2/3) rd the translational kinetic energy for each molecule.
 The total kinetic energy of 8 litres of helium molecules at 5 atmosphere pressure will be
(1 atmosphere = 1.013×105pascal)
  • 607 J
  • 6078 J
  • 607 erg
  • 6078 erg
2 grams of mono atomic gas occupies a volume of 2 litres at a pressure of 8.3×105 Pa and 1270C. Find the molecular weight of the gas.
  • 2 grams/mole
  • 16 grams/mole
  • 4 grams/mole
  • 32 grams/mole
Two moles of an ideal gas X occupying a volume V excert a pressure P. The same pressure is excert by one mole of another gas Y occupying a volume 2V. (if the molecular weight of Y is 16 times the molecular weight of X), find the ratio of the 'rms' speed of the molecular of X and Y.
  • 2
  • 4
  • 12
  • 2
The temperature of a diatomic gas is T. The total kinetic energy of the gas is given as E=K1 where K1 is constant. Find out the total number of molecules of the gas in the sample. (K = Boltzaman's constant)
  • 3K1K
  • 5K1/2K
  • 2K1/5K
  • None of these
let A and B the two gases and given :
TAMA =TBMB  Where T is the temperature and M is molecular mass. If CA and  CB are the r.m.s. speed, then the ratio CACB will be equal to:
  • 2
  • 4
  • 1
  • 0.5
If hydrogen gas is heated to a very high temperature, then the fraction of energy possessed by gas molecules correspond to rotational motion:-
  • 35
  • 27
  • 37
  • 25
A gas is filled in a cylinder. Its temperature is increased by 20% and volume decreases by 20%. If pressure remains constant, what percentage of mass of the gas leaks out?
  • 33.33%
  • 66.67%
  • 20%
  • 40%
The rms speed of N2 molecular at STP (P=1 tm; T=00C) is.....
(the density of N2 in these conditions is 1.25 kg/m3
  • 493 m/s
  • 390 m/s
  • 290 m/s
  • 590 m/s
An ant is moving on a plane horizontal surface. The number of degrees of freedom of the ant will be
  • 1
  • 2
  • 3
  • 6
When 2gm of gas is introduced into an evacuated flask kept at 25oC the pressure is found to be one atmosphere. If 3gm of another gas added to the same flask the pressure becomes 1.5 atmospheres. The ratio of the molecular weights of there gases will be
  • 1:3
  • 3:1
  • 1:2
  • 3:2
If γ be the ration of specific heats of a perfect gas, the number of degree of freedom of a molecule of the gas is:
  • 252(γ1)
  • 3γ12γ1
  • 2γ1
  • 92(γ1)
The degree of freedom of a diatomic gas at normal temperature is.
  • 7
  • 6
  • 5
  • 4
A real gas most closely approaches the behaviour of an ideal gas at :
  • 15 atm and 200 K
  • 1 atm and 273 K
  • 0.5 atm and 500 K
  • 15 atm and 500 K
When an ideal monoatomic  gas is heated zt constant pressure , which of the following may be true
  • dUdQ=35
  • dWdQ=2]5
  • dUdQ=45
  • dW+dU=dQ
A gas mixture contains 8 moles of oxygen and 2 mole of argon at room temperature T. The total energy of the mixture is 
  • 11 RT
  • 23 RT
  • 22 RT
  • 26 RT
The kinetic energy for 14 grams of nitrogen gas at  127  is nearly (mol. mass of nitrogen  =28  and gas constant  =8.31JK1mol1 )
  • 1.0J
  • 4.15J
  • 2493J
  • 3.3J
0:0:2


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