Physics Practice MCQ Page 44

Multiple Choice questions for Physics in the sets of 10 each on one page with questions and answers. All sets are useful in the preparation of subject tests for employment or admission.
Question: 3979   consider the following statements Assertion (A): CO2 lasers are much more efficient than other lasers Reason (R): the vibrational rotational levels of the lowest electronic state are involved in the CO2 laser transitions of these statements
  1. both A and R are true and R is the correct explanation of A
  2. both A and R are true but is not a correct explanation of A
  3. A is true but R is false
  4. A is false but R is true
Question: 3982   When the temperature of a gas is increased at constant pressure, the potential energy of the molecules
  1. increases but their kinetic energy decreases
  2. decreases but their kinetic energy increases
  3. as well as their kinetic energy decrease
  4. as well as their kinetic energy increase
Question: 3983   The theoretical values of the molar specific heats of solids, deduced on the basis of the law of equipartition of energy are always smaller than their experimental values. This discrepancy is attributed to the
  1. exclusion of the electronic contributions to specific heats
  2. errors in the measurements of specific heats
  3. approximations in the calculations of specific heats
  4. non-zero values of the thermal expansion coefficients
Question: 3985   Oxygen gas with an initial volume of 8 m3 is allowed to expand from 4 atmospheres to 1 atmosphere. Once the equilibrium temperature is reached, the gas is compressed to its original volume. If the final entropy were higher than its initial entropy, the the gas had undergone.
  1. adiabatic expansion and isothermal compression
  2. isothermal expansion and adiabatic compression
  3. free expansion and isothermal compression
  4. adiabatic expansion and isobaric compression
Question: 3987   The pressure on a block of silver is increased quasi-statically and isothermally from 1 to 2000 atmospheres. The amount of heat liberated during this process is
  1. exactly equal to the work done
  2. more than the change in the internal energy
  3. less than the change in the internal energy
  4. less than the work done
Question: 3989   Colliodal particles of mass M are suspended in a gas at 300 K and 1 atmosphere. The most probable energy of these particles is equal to the kinetic energy of a gas molecule moving with the most probable velocity, vp, at the temperature
  1. 450 K
  2. 380 K
  3. 300 K
  4. 150 K
Question: 3990   The temperature of a gas is held constant while its volume is decreased. The pressure exerted by the gas on the walls of the container increases because its molecules
  1. strike the walls with higher velocities
  2. strike the walls with larger force
  3. strike the walls more frequently
  4. are in contact with the walls for a shorter time
Question: 3992   A nonconducting partition divides a container into two equal compartments. One is filled with helium gas at 400 K and the other is filled with carbon monoxide gas at 240 K. The number molecules in each gas is the same. If the partition is removed to allow the gases to mix, then the final equilibrium temperature will be
  1. 300 K
  2. 320 K
  3. 340 K
  4. 352 K
Question: 3995   The viscosity of a gas arises from the transport of momentum from 'high velocity' to ' low velocity' region. The mean square velocity of those molecules which carry momentum across a hypothetical layer of the gas is given by
  1. kt/m
  2. 2kT/m
  3. 2.5 kT/m
  4. 4 kT/m
Question: 3996   According to Planck's law of black body radiation a hotter body radiates
  1. most of the energy in the longer wavelength region
  2. most of the energy in the shorter wavelength region
  3. equal amount of energy in all regions of wavelengths
  4. energy in bands separated by gaps
Question: 3998   The Joule Thomson expansion produces cooling
  1. at all initial temperatures and pressures
  2. above certain initial temperature
  3. above certain initial pressure
  4. below certain initial temperature
Question: 3999   Consider the following statements Assertion (A): the root mean square velocity of molecules of a gas having Maxwellian distribution of velocities, is higher than their most probable velocity, at any temperature Reason (R): A very small number of molecules of a gas which posses very large velocities increase the root mean square velocity, without affecting the most probable velocity of these statement
  1. both A and R are true and R is the correct explanation of A
  2. both A and R are true but R is not a correct explanation of A
  3. A is true but R is false
  4. A is false but R is true

Answers to the questions of Physics on this page

Following list gives the correct choice for the answer of the Physics mcqs.
3979 . A       3982 . B       3983 . D       3985 . B       3987 . D       3989 . C       3990 . A       3992 . B       3995 . A       3996 . C       3998 . D       3999 . A      

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