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Aerodynamics Mcqs

Q:

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
 
Answer & Explanation Answer: B) Kinetic energy between the molecules

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.

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Q:

The chemical and vibrational process occur due to molecular collision.

A) True B) False
 
Answer & Explanation Answer: A) True

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.

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Q:

What happens to a reaction when reaction quotient is equal to the equilibrium constant?

A) Forward reaction B) Equilibrium
C) Reverse reaction D) No change
 
Answer & Explanation Answer: C) Reverse reaction

Explanation: The reaction quotient gives the same expression as the equilibrium constant for a reaction that is at chemical equilibrium. But, for a reaction when the reaction quotient (Q) is greater than the equilibrium constant (k), there’s more product than the reactant and reverse reaction takes place.

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Q:

What is chemical equilibrium?

A) Change in temperature spontaneously B) No change in chemical composition spontaneously
C) Change in pressure D) Equilibrium between mole fractions
 
Answer & Explanation Answer: B) No change in chemical composition spontaneously

Explanation: In a mixture of gases (air), when there is no sudden change in the chemical composition spontaneously or over a short period of time, the system is known to be in chemical equilibrium. There are no changes in temperature, velocity, pressure in the system.

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Q:

What is Dalton’s law?

A) Total temperature is equal to sum of partial temperatures B) Total entropy is equal to sum of partial entropies
C) Total pressure is equal to sum of partial pressures D) Total number of moles is equal to sum of mole fractions
 
Answer & Explanation Answer: C) Total pressure is equal to sum of partial pressures

Explanation: Dalton’s law of partial pressure was formulated to find out the total pressure of the chemically reactive mixture. This is the sum of partial pressures of individual components in the mixture. Dalton’s law is only applicable or perfect gases which means that the intermolecular forces between individual molecules is negligible.

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31
Q:

Which of these methods is not used in describing the composition of air which is at a chemical equilibrium?

A) Partial pressure B) Partial temperature
C) Mass fraction D) Mole – mass ratio
 
Answer & Explanation Answer: B) Partial temperature

Explanation: There are several ways to describe the composition of air which is at a chemical equilibrium. These are – partial fraction, concentration, mole fraction, mole – mass fraction and mass fraction. These help in determining the composition of the reacting gas.

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Q:

At high temperature, there’s presence of only oxygen and nitrogen molecules in the air.

A) True B) False
 
Answer & Explanation Answer: B) False

Explanation: Not available for this question

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30
Q:

How does the probability of finding molecule in an energy state vary?

A) Parabolic B) Exponential
C) Hyperbolic D) Linear
 
Answer & Explanation Answer: B) Exponential

Explanation: On observing the equation of finding the molecule in a particular energy state as given by Boltzmann distribution law, we see that the graph varies exponentially as energy ?j divided by kT (where k is the Boltzmann constant).

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