Engineering Questions with Answers - Multiple Choice Questions

MCQs on Introduction to Nonequilibrium Systems

1 - Question

The chemical and vibrational process occur due to molecular collision.
a) True
b) False

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Explanation: All the vibrational and chemical processes occur by the process of molecular collision. When the molecules collide, there is a change between the vibrational energy before and after the collision which is dependent on the temperature and kinetic energy.

2 - Question

Which of these parameters affect the number of collisions?
a) Pressure of the setup
b) Kinetic energy between the molecules
c) Density of the apparatus
d) Temperature of the apparatus

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Explanation: For a molecule to become vibrationally excited, it has to undergo several number of collisions which is affected by the kinetic energy present between these colliding particles. Higher kinetic energy results in higher gas temperature which eventually leads to lesser number of collisions required for the molecule to become vibrationally excited.

3 - Question

Time taken for the number of collisions depends on which of these parameters?
a) Molecular collision frequency
b) Molar density
c) Number of moles
d) Boltzmann constant

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Explanation: The amount of time taken by the molecules for collision depends on the molecular collision frequency. Thus parameter tells how many collisions take place with a neighboring particle in a second for a single particle.

4 - Question

If the temperature increases, what happens to the molecular collision frequency?
a) Increases
b) Decreases
c) No change
d) First increases then decreases

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Explanation: The molecular collision frequency (Z) is given by the relation:
Z ∝ pT√
Therefore, molecular collision frequency is inversely proportional to the square root of temperature which means that as the temperature increases, collision frequency decreases.

5 - Question

For which condition is collision theory low?
a) Low temperature and pressure
b) High temperature and pressure
c) Low temperature, high pressure
d) High temperature, low pressure

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Explanation: Molecular collision frequency is directly proportional to the pressure of the molecule and inversely proportional to the square root of the temperature. Therefore, for obtaining low collision frequency, the pressure should be low and the temperature should be high.

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