NEET Physics Speed of Gas Pressure and Kinetic Energy MCQs Set A

Question. Reason : The mean square velocity of the molecules is inversely proportional to mass.
a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
b) Assertion is correct, reason is incorrect
c) Assertion is correct, reason is correct; reason is a correct explanation for assertion
d) Assertion is incorrect, reason is correct.

Answer: A

Question:  The root mean sqaure velocity of the molecules in a sample of helium is 5/7 th that of the molucules in a sample of hydrogen. If the temperature of hydrogen sample is 0oC, that of helium sample is about
a) 0^oC
b) 283 K
c) 0K
d) 100^oC

Answer: A

Question: The root mean square velocity of hydrogen molecules at 300 K is 1930 metre/sec. Then the r.m.s velocity of oxygen molecules at 1200 K will be
a) 965 metre/sec
b) 3860 metre/sec
c) 482.5 metre/sec
d) 1930 metre/sec

Answer: A

Question: At what temperature the mean speed of the molecule of hydrogen gas (H2) equals the escape speed from the earth?
a) 11800 K
b) 1500 K
c) 1800 K
d) 2000 K

Answer: A

Question.  The average kinetic energy of gas molecules depends upon which of the following factor?
(a) Temperature of the gas
(b) Nature of the gas
(c) Volume of the gas
(d) None of these

Answer: A

Question.  The temperature of a gas is a measure of
(a) the average kinetic energy of the gaseous molecules
(b) the average potential energy of the gaseous molecules
(c) the size of the molecules of the gas
(d) the average distance between the molecules of the gas

Answer: A

Question. In the isothermal expansion of 10g of gas from volume V to 2V the work done by the gas is 575J. What is the root mean square speed of the molecules of the gas at that temperature?
(a) 499m/s
(b) 532m/s
(c) 520m/s
(d) 398m/s

Answer: A

Question. In a diatomic molecules, the rotational energy at a given temperature
(a) obeys Maxwell’s distribution
(b) have the same volue for all molecules
(c) equals the translational kinetic energy for each molecule
(d) None of these

Answer: A

Question. Assertion : When we place a gas cylinder on a moving train, its internal kinetic energy increases.
Reason : Its temperature remains constant.
(a) Assertion is correct, reason is incorrect
(b) Assertion is incorrect, reason is correct
(c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question.  Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will.
(a) remains the same
(b) decrease for some and increase for others
(c) decrease
(d) increase

Answer: A

Question.  Pressure exerted by a gas is
(a) directly proportional to the density of the gas
(b) directly proportional to the square of the density of the gas
(c) inversely proportional to the density of the gas
(d) independent of density of the gas

Answer: A

Question.  At a given temperature which of the following gases possesses maximum r.m.s. velocity?
(a) Hydrogen
(b) Oxygen
(c) Nitrogen
(d) Carbon dioxide

Answer: A

Question. The internal energy of an ideal gas is
(a) the total kinetic energy of gas molecules
(b) the total kinetic energy of randomly moving molecules
(c) the total translational kinetic energy.
(d) the sum of total kinetic and potential energies

Answer: A

Question.  Maxwell's laws of distribution of velocities shows that
(a) the number of molecules with most probable velocity is very large
(b) the number of molecules with most probable velocity is very small
(c) the number of molecules with most probable velocity is zero
(d) the number of molecules with most probable velocity is exactly equal to 1

Answer: A

Question.  For mean kinetic energy per molecule, a vessel filled with two different gases.
I. Mean kinetic energy per molecule for both gases will be equal.
II. Mean kinetic energy per molecule of gas with higher mass will be more.
III. Mean kinetic energy per moleculers of gas with lower mass will be more.
Select the correct statement(s).
(a) I only
(b) I and II
(c) II only
(d) I, II and III

Answer: A

Question. A flask contains a monoatomic and a diatomic gas in the ratio of 4 : 1 by mass at a temperature of 300 K. The ratio of average kinetic energy per molecule of the two gases is
(a) 1 : 1
(b) 2 : 1
(c) 4 : 1
(d) 1 : 4

Answer: A

Question.  At constant volume, temperature is increased then
(a) number of collisions per unit time will increase
(b) collisions will be in straight lines
(c) collisions will not change
(d) collision on walls will be less

Answer: A

Question. Gas at a pressure P₀ is contained in a vessel. If the masses of all the molecules are halved and their speeds are doubled, the resulting pressure P will be equal to
(a) 2P₀
(c) P₀
(d) 6P₀

Answer: A

Question.  Which of the following is/are incorrect statement(s) regarding the law of equipartition of energy ?
I. The gas possess equal energies in all the three directions x,y and z-axis.
II. The total energy of a gas is equally divided between kinetic and potential energies.
III. The total kinetic energy of a gas molecules is equally divided among translational and rotational kinetic energies.
(a) II and III
(b) I, II and III
(c) I and III
(d) I only

Answer: A

Question.  The temperature at which the average transitional kinetic energy of a gas molecule is equal to the energy gained by an electron in accelerating from rest through a potential difference of 1 volt is
(a) 7.7 × 10³ K
(b) 11.6 × 10³ K
(c) 4.6 × 10³ K
(d) 23.2 × 10³ K

Answer: A

Question.  The temperature at which protons in hydrogen gas would have enough energy to overcome Coulomb barrier of 4.14 × 10^–14 J is (Boltzmann constant = 1.38 × 10^–23 JK^–1)
(a) 2 × 10⁹ K
(b) 6 × 10⁹ K
(c) 10⁹ K
(d) 3 × 10⁹ K

Answer: A

Question. The temperature at which oxygen molecules have the same root mean square speed as that of hydrogen molecules at 300 K is
(a) 4800 K
(b) 300 K
(c) 2400 K
(d) 600 K

Answer: A

Question. Assertion : If a gas container in motion is suddenly stopped, the temperature of the gas rises.
Reason : The kinetic energy of ordered mechanical motion is converted in to the kinetic energy of random motion of gas molecules.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question.  One kg of a diatomic gas is at a pressure of 8 × 10⁴N/m². The density of the gas is 4kg/m³. What is the energy of the gas due to its thermal motion?
(a) 5 × 10⁴ J
(b) 7 × 10⁴ J
(c) 3 × 10⁴ J
(d) 6 × 10⁴ J

Answer: A

Question. The kinetic theory of gases states that the average squared velocity of molecules varies linearly with the mean molecular weight of the gas. If the root mean square (rms) velocity of oxygen molecules at a certain temperature is 0.5 km/sec. The rms velocity for hydrogen molecules at the same temperature will be :
(a) 2 km/sec
(b) 4 km/sec
(c) 8 km/sec
(d) 16 km/sec

Answer: A

Question. Find the temperature at which the Vrms for O² molecule is 483 ms^–1
(a) 300 K
(b) 400 K
(c) 500 K
(d) 600 K

Answer: A

Question.  The r.m.s. velocity of oxygen molecule at 16ºC is 474 m/sec. The r.m.s. velocity in m/s of hydrogen molecule at 127ºC is
(a) 2230.59
(b) 2730
(c) 1896
(d) 1603

Answer: A

Question. Assertion : For an ideal gas, at constant temperature, the product of pressure and volume is constant.
Reason : The mean square velocity of the molecules is inversely proportional to mass.
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is incorrect
(c) Assertion is correct, reason is correct; reason is a correct explanation for assertion
(d) Assertion is incorrect, reason is correct.

Answer: A

Question.  The root mean sqaure velocity of the molecules in a sample of helium is 5/7 th that of the molucules in a sample of hydrogen. If the temperature of hydrogen sample is 0oC, that of helium sample is about
(a) 0^oC
(b) 283 K
(c) 0K
(d) 100^oC

Answer: A

Question. The root mean square velocity of hydrogen molecules at 300 K is 1930 metre/sec. Then the r.m.s velocity of oxygen molecules at 1200 K will be
(a) 965 metre/sec
(b) 3860 metre/sec
(c) 482.5 metre/sec
(d) 1930 metre/sec

Answer: A

Question. At what temperature the mean speed of the molecule of hydrogen gas (H2) equals the escape speed from the earth?
(a) 11800 K
(b) 1500 K
(c) 1800 K
(d) 2000 K

Answer: A

Question.  The average transitional energy and the rms speed of molecules in a sample of oxygen gas at 300 K are 6.21 × 10^–21 J and 484 m/s respectively. The corresponding values at 600 K are nearly (assuming ideal gas behaviour)
(a) 12.42 × 10^–21 J, 684 m/s
(b) 8.78 × 10^–21 J, 684 m/s
(c) 12.42 × 10^–21 J, 968 m/s
(d) None of these

Answer: A