Water Resources · MCQ practice Properties of Fluid MCQs – Part 5
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Part 5 of 6 Question 61 Easy
Viscosity of water in comparison to mercury is:
A Higher B Lower C Same D Higher/lower depending on temperature
Answer: B. Lower
The dynamic viscosity of water (~1.0 cP at 20°C) is lower than that of mercury (~1.55 cP at 20°C).
Question 62 Easy
A hydrometer is used to measure:
A Velocity of fluids B Velocity of gases C Flow of fluids D Specific gravity of liquids
Answer: D. Specific gravity of liquids
A hydrometer floats in a liquid to measure its specific gravity (relative density) directly based on Archimedes' buoyancy principle.
Question 63 Easy
When the cohesion between molecules of a fluid is greater than adhesion between fluid and the glass, then the free level of fluid in glass tube dipped in the glass vessel will be:
A Same as the surface of the fluid B Lower than the surface of the fluid C Higher than the surface of the fluid D Dependent on atmospheric pressure
Answer: B. Lower than the surface of the fluid
When cohesion exceeds adhesion, capillary depression occurs and the liquid level inside the tube drops lower than the surrounding liquid surface.
Question 64 Easy
Viscous force is the ............. of shear stress due to viscosity and cross sectional area of flow:
A Sum B Product C Difference D Ratio
Answer: B. Product
Viscous force is shear stress multiplied by contact area: F = τ × A.
Question 65 Easy
Viscosity of a fluid with specific gravity 1.3 is measured to be 0.0034 Ns/m². Its kinematic viscosity, in m²/s, is:
A 2.6 × 10⁻⁶ B 4.4 × 10⁻⁶ C 5.8 × 10⁻⁶ D 7.2 × 10⁻⁶
Answer: A. 2.6 × 10⁻⁶
Kinematic viscosity ν = μ / ρ = 0.0034 / (1.3 × 1000) = 0.0034 / 1300 ≈ 2.615 × 10⁻⁶ m²/s.
Question 66 Medium
Surface tension:
A Acts in the plane of interface normal to any line in the surface B Is also known as capillarity C Is a function of the curvature of the interface D Decreases with fall in temperature
Answer: A. Acts in the plane of interface normal to any line in the surface
Surface tension is a tensile force that acts tangential to the liquid interface and perpendicular (normal) to any line drawn on the surface.
Question 67 Easy
Flow of fluid take place due to its:
A Viscosity B Compressibility C Surface tension D Deformation under shear force
Answer: D. Deformation under shear force
A fluid is defined as a substance that continuously deforms (flows) under the application of shear stress, no matter how small.
Question 68 Easy
Poise is the unit of:
A Mass density B Kinematic viscosity C Viscosity D Velocity gradient
Answer: C. Viscosity
Poise is the CGS unit of dynamic viscosity (1 poise = 1 dyne·s/cm² = 0.1 Pa·s).
Question 69 Easy
Which of the following fluids can be classified as non–newtonian?
A Kerosene oil and Diesel Oil B Human blood and Toothpaste C Diesel oil and Water D Kerosene oil and Water
Answer: B. Human blood and Toothpaste
Human blood (pseudoplastic) and toothpaste (Bingham plastic) do not follow Newton's linear law and are classified as non-Newtonian fluids.
Question 70 Easy
With increase in temperature the viscosity of air and water varies as?
A Viscosity of air increases and viscosity of water increases B Viscosity of air decreases and viscosity of water decreases C Viscosity of air decreases and viscosity of water increases D Viscosity of air increases and viscosity of water decreases
Answer: D. Viscosity of air increases and viscosity of water decreases
With rising temperature, the viscosity of air (a gas) increases due to molecular collisions, while the viscosity of water (a liquid) decreases due to weakened cohesion.
Question 71 Easy
Capillarity is due to: I. surface tension, II. cohesion, III. viscosity, IV. vapour pressure, V. weight density of liquid
A II, III B III C I D II, III, V
Answer: C. I
Capillarity is primarily caused by surface tension at the curved liquid meniscus balancing the weight of the elevated or depressed column.
Question 72 Easy
A fluid, which is incompressible and is having no viscosity is:
A Newtonian fluid B Non Newtonian C Ideal fluid D Real fluid
Answer: C. Ideal fluid
An imaginary fluid having zero viscosity and zero compressibility (constant density) is defined as an ideal fluid.
Question 73 Easy
Capillary rise a phenomenon that is attributed to the following property of fluid:
A density B surface tension C vapour pressure D viscosity
Answer: B. surface tension
Capillary rise is directly caused by surface tension pulling the liquid upward against gravity.
Question 74 Easy
Bulk modulus of a fluid is the ratio of:
A shear stress to shear strain B increase in volume to the viscosity of fluid C increase in pressure to the volumetric strain D critical velocity to the velocity of fluid
Answer: C. increase in pressure to the volumetric strain
Bulk modulus K is defined as the ratio of increase in compressive pressure to volumetric strain: K = −dp / (dV/V).
Question 75 Easy
The ratio of specific weight of a liquid to the specific weight of pure water at a standard temperature is called:
A density of liquid B specific gravity of liquid C compressibility of liquid D surface tension of liquid
Answer: B. specific gravity of liquid
Specific gravity is the ratio of a liquid's specific weight (or density) to that of pure water at standard temperature.
Part 5 of 6