Explore topic-wise MCQs in Engineering Physics.

This section includes 90 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering Physics knowledge and support exam preparation. Choose a topic below to get started.

51.

If 400 ml of gas is pressurised from 1 atm to 2.5 atm then find its new volume (in ml) given temperature has not changed?

A. 1000
B. 250
C. 160
D. 500
Answer» D. 500
Discussion
52.

At what temperature (in °C) is the r.m.s. velocity of hydrogen molecules twice the r.m.s. velocity of oxygen molecules at 327° C

A. 150
B. - 123
C. -150
D. 123
Answer» C. -150
Discussion
53.

At a certain temperature "oxygen" molecules have r.m.s. velocity 2 km/s. What is the r.m.s. velocity (in km/s) of hydrogen molecules at that temperature?

A. 4
B. 8
C. 0.5
D. 16
Answer» C. 0.5
Discussion
54.

For a given gas at 1 atm pressure, rms speed of the molecules is 200 m/s at 127°C. At 2 atm pressure and at 227°C, the rms speed of the molecules will be:

A. 100 m/s
B. \(80\sqrt 5 \:m/s\)
C. \(100\sqrt 5 \:m/s\)
D. 80 m/s
Answer» D. 80 m/s
Discussion
55.

Each mode of vibration for a molecule like CO contributes _________ to the energy of a molecule.

A. 2kBT
B. kBT / 4
C. kBT / 2
D. kBT
Answer» E.
Discussion
56.

For a mole of a solid, the total energy is equal to?

A. 2RT
B. 3RT
C. RT
D. 4RT
Answer» C. RT
Discussion
57.

If ratio of root mean square (r.m.s.) velocities of the molecules of two gases A (molecular mass 18) and B (molecular mass 2) is 1:6, and temperatureof B is 800K then what is temperature of A (in K)?

A. 200
B. 400
C. 100
D. 300
Answer» B. 400
Discussion
58.

A 25 × 10-3 m3 volume cylinder is filled with 1 mol of O2 gas at room temperature (300 K). The molecular diameter of O2, and its root mean square speed, are found to be 0.3 nm and 200 m/s, respectively. What is the average collision rate (per second) for an O2 molecule?

A. ~1012
B. ~1011
C. ~1010
D. ~1013
Answer» E.
Discussion
59.

If the pressure on an enclosed gas is doubled and its temperature rises from 27°C to 127°C then its volume will ________________

A. increase by 1/3rd
B. decrease by 1/3rd
C. decrease by 2/3rd
D. increase by 2/3rd
Answer» C. decrease by 2/3rd
Discussion
60.

An electron, moving along the x-axis with an initial energy of 100 eV, enters a region of magnetic field \(\vec B = \left( {1.5 \times {{10}^{ - 3}}T} \right)\hat k\) at S (see figure). The field extends between x = 0 and x = 2 cm. The electron is detected at the point Q on a screen placed 8 cm away from the point S. The distance d between P and Q (on the screen) is:(Electron’s charge = 1.6 × 10-19 C; Mass of the electron = 9.1 × 10-31 kg

A. 11.65 cm
B. 12.87 cm
C. 1.22 cm
D. 2.25 cm
Answer» C. 1.22 cm
Discussion
61.

For a diatomic molecule free to move in space, the sum of it's translational and rotational degrees of freedom is ___________.

A. four
B. five
C. three
D. two
Answer» C. three
Discussion
62.

For a polyatomic gas which has f vibrational modes, Cp is equal to? (Cp is molar specific heat at constant pressure)

A. (4 + f)R
B. (3 + f)R
C. (5 + f)R
D. (2 + f)R
Answer» B. (3 + f)R
Discussion
63.

If the volume of a gas at 127°C doubles then what will be the final temperature (in°C), if pressure remains unchanged?

A. 327
B. 527
C. 800
D. 600
Answer» C. 800
Discussion
64.

If a diatomic molecule is not rigid but has in addition a vibrational mode, then its Cp is equal to? (Cp is molar specific heat at constant pressure)

A. 7R/2
B. 5R/2
C. 3R/2
D. 9R/2
Answer» E.
Discussion
65.

Molecules of Oxygen have how many degrees of freedom? (Assume molecules are rigid)

A. four
B. three
C. five
D. two
Answer» D. two
Discussion
66.

22.4 litres of any gas at S.T.P. contains _________________ particles.

A. 6.02 × 1022
B. 2.06 × 1023
C. 6.02 × 1023
D. 2.06 × 1022
Answer» D. 2.06 × 1022
Discussion
67.

Change in enthalpy in a closed system is equal to the heat transferred, if the reversible process takes place at constant

A. Temperature
B. Internal energy
C. Pressure
D. Entropy
Answer» D. Entropy
Discussion
68.

In Maxwell-Boltzmann distribution, the fraction of gas molecules having energy between E and E + dE is proportional to

A. \({E^{\frac{1}{2}}}\exp \left( { - \frac{E}{{kT}}} \right)\)
B. \({E^{\frac{3}{2}}}\exp \left( { - \frac{E}{{kT}}} \right)\)
C. \({E^{\frac{1}{2}}}\)
D. \({E^{\frac{3}{2}}}\exp \left( {\frac{E}{{kT}}} \right)\)
Answer» B. \({E^{\frac{3}{2}}}\exp \left( { - \frac{E}{{kT}}} \right)\)
Discussion
69.

In the relation from Kinetic theory of gases, PV = (1/3)Nmv2, if 'N' is number of particles then 'm' stands for?

A. Molecular mass
B. Mass of the gas
C. Mass of the particle
D. Number of moles of the gas
Answer» D. Number of moles of the gas
Discussion
70.

A diatomic molecule has _________ rotational degrees of freedom.

A. two
B. three
C. zero
D. one
Answer» B. three
Discussion
71.

If the gas particles are of diameter 'd', average speed 'v', number of particles per unit volume 'n', then the average distance between two successive collisions, called the mean free path is ______.

A. 1/(n2πd)
B. 1/(nπd2)
C. 1/(nπ2d)
D. 1/(nπdv2)
Answer» C. 1/(nπ2d)
Discussion
72.

How many molecules are likely to be present in a cubic centimeter of volume if the pressure is 20 mm of Hg and the temperature is 27°C?

A. 6.4 x 1017
B. 6.4 x 1023
C. 4.8 x 1015
D. 4.8 x 1021
Answer» B. 6.4 x 1023
Discussion
73.

If the degree of freedom of a gas is n, then the ratio of CP and CV is

A. \(1 + \frac{2}{n}\)
B. \(1 + \frac{1}{n}\)
C. \(1 + \frac{1}{{2n}}\)
D. \(\frac{{2n}}{{2n + 1}}\)
Answer» B. \(1 + \frac{1}{n}\)
Discussion
74.

If a gas in a fixed volume container is heated, the resultant pressure on the gas

A. remains the same
B. increases
C. decreases
D. is inversely proportional to the heat
Answer» C. decreases
Discussion
75.

Automobile exhaust is an important element involved in automobile exhaust.A. FluorineB. SodiumC. MagnesiumD. Lead

A. B
B. D
C. A
D. C
Answer» C. A
Discussion
76.

In the relation from Kinetic theory of gases, "PV = (1/3)Nmv2", if 'm' is the mass of the particle then 'N' stands for _________________.

A. number of moles of the gas
B. number of particles
C. Avogadro's number
D. number of collisions per unit volume
Answer» C. Avogadro's number
Discussion
77.

If the r.m.s. velocities of the molecules of two gases 'A' (at 500K) and 'B' (at 300K) are 500m/s and 100m/s respectively, then find molecular mass of the 'B' if molecular mass of 'A' is 2?

A. 15
B. 60
C. 30
D. 12
Answer» D. 12
Discussion
78.

10 grams of a gas occupies 5.6 L of volume at S.T.P. The vapour density & formula of the compound are:

A. 40 & C6H8
B. 40 & C3H4
C. 80 & C6H8
D. 20 & C3H4
Answer» E.
Discussion
79.

If gas is enclosed in a container which is then placed on a fast moving train. The temperature of the gas ______.

A. Falls
B. Remain unchanged
C. Becomes unsteady
D. Rises
Answer» C. Becomes unsteady
Discussion
80.

At what temperature, the rms velocity of hydrogen molecule will be equal to the rms velocity of oxygen molecule at 47°C?

A. 20°C
B. 20 K
C. 5.8°C
D. 273°C
Answer» C. 5.8°C
Discussion
81.

A_BULB_CONTAINS_ONE_MOLE_OF_HYDROGEN_MIXED_WITH_ONE_MOLE_OF_OXYGEN_AT_TEMPERATURE_T._THE_RATIO_OF_RMS_VALUES_OF_VELOCITY_OF_HYDROGEN_MOLECULES_TO_THAT_OF_OXYGEN_MOLECULES_IS?$

A. 1:16
B. 1:4
C. 4:1
D. 16:1
Answer» D. 16:1
Discussion
82.

The degree of freedom of a triatomic gas is
A. 1
B. 2
C. 6
D. 8
Answer» D. 8
Discussion
83.

The temperature of gas is held constant, while its volume is decreased. The pressure exerted by the gas on the wall of the container increases, because of its molecule?
A. Strike the walls with higher velocities
B. Strike the walls with large farce
C. Strike the walls more frequently
D. Are in contact with the walls for a shorter time
Answer» D. Are in contact with the walls for a shorter time
Discussion
84.

A gas behaves as an ideal gas at

A. Low pressure and high temperature
B. Low pressure and low temperature
C. High pressure and low temperature
D. High pressure and high temperature
Answer» B. Low pressure and low temperature
Discussion
85.

For Boyle’s law to hold good, the gas should be$

A. Perfect and of constant mass and temperature
B. Real and of constant mass and temperature
C. Perfect and at constant temperature but variable mass
D. Real and at constant temperature but variable mass
Answer» B. Real and of constant mass and temperature
Discussion
86.

At Boyle’s temperature$

A. Joule’s effect is positive
B. Van der Waal’s equation becomes zero
C. Gases obey Boyle’s law
D. Water solidifies
Answer» D. Water solidifies
Discussion
87.

Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will

A. Increase
B. Decrease
C. Remain the same
D. Decreases for some, while the increase for others
Answer» D. Decreases for some, while the increase for others
Discussion
88.

The ration of the speed of sound in nitrogen gas to that in helium gas, at 300 K is

A. ‚àö(2/7)
B. ‚àö(1/7)
C. ‚àö3/5
D. ‚àö6/5
Answer» D. ‚Äö√Ñ√∂‚àö‚Ć‚àö‚àÇ6/5
Discussion
89.

What is the average velocity of the molecules of an ideal gas?

A. Infinity
B. Constant
C. Unstable
D. Zero
Answer» E.
Discussion
90.

On which factor does the average kinetic energy of gas molecules depend?
A. Nature of the gas
B. Temperature
C. Volume
D. Mass
Answer» C. Volume
Discussion