Engineering Chemistry Questions and Answers – Viscosity

This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Viscosity”.

1. According to Newton’s law of viscosity, the maximum velocity of flow is at __________
a) Top of the tube
b) Bottom of the tube
c) Middle of the tube
d) It is same at all the places

Explanation: According to Newton’s law of viscosity, the maximum velocity of flow is at the middle of the tube. It states that for given shear stress acting on a fluid element, the rate at which the fluid deforms is inversely proportional to the viscosity.

2. The factor on which viscosity depends is __________
a) Area of contact of two adjacent layers
b) Velocity difference between two adjacent layers
c) The distance between two adjacent layers
d) All of the mentioned

Explanation: The factors on which viscosity depends are- Area of contact of two adjacent layers, velocity difference between two adjacent layers and the distance between two adjacent layers.

3. The viscosity of a fluid is inversely proportional to the __________
a) Area of contact of two adjacent layers
b) Distance between two adjacent layers
c) Velocity difference between two adjacent layers
d) None of the mentioned

Explanation: The viscosity of a fluid is inversely proportional to the distance between two adjacent layers.

4. The Newton’s law of viscosity is not applicable to __________
a) Turbulent flow
b) Laminar flow
c) Streamline flow
d) All of the mentioned

Explanation: The Newton’s law of viscosity is not applicable to turbulent flow. According to Newton’s law of viscosity, for a given shear stress acting on a fluid element, the rate at which the fluid deforms is inversely proportional to the viscosity.

5. What is the dimension of viscosity?
a) MLT2
b) M1L-1T
c) ML-1T-1
d) ML-2T1

Explanation: The dimension of viscosity is ML-1T-1. It’s unit is m2/s or stokes.
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6. The absolute kinematic viscosity is the ratio of __________
a) Density to absolute viscosity
b) Absolute viscosity to density
c) Kinetic energy to absolute viscosity
d) Absolute viscosity to kinetic energy

Explanation: The absolute kinematic viscosity is the ratio of absolute viscosity to density for any fluid.

7. On increasing the temperature, the viscosity of the fluid __________
a) Decreases
b) Increases
c) Remains constant
d) None of the mentioned

Explanation: On increasing the temperature, the viscosity of the fluid decreases. This is because of the decrease in inter-molecular forces.

8. How does viscosity gets affected on increasing the pressure?
a) Viscosity increases
b) Viscosity decreases
c) Viscosity does not get affected by the pressure
d) None of the mentioned

Explanation: At high pressures, the viscosity increases considerably. Zero viscosity is observed only at very low temperatures in superfluids.

9. Select the incorrect statement from the following option.
a) Viscosity helps in the selection of good lubricating oil
b) Light oils have low densities and easy flowability
c) Heavy oils are used on parts moving with high speed
d) Light oils do not impose much drag on high-speed parts

Explanation: Heavy oils are used on parts moving with slow speed under heavy loads. All the other options are correct. Viscosity helps in the selection of good lubricating oil, light oils have low densities and easy flowability and do not impose much drag on high-speed parts.

10. 1 poise = ___________
a) 10 N sm-2
b) 100 N sm-2
c) 1/100 N sm-2
d) 1/10 N sm-2

Explanation: 1 poise = 1 dyne s cm-2 = 1/10 N s m-2.

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