This set of Nanotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Nanofluidics”.
1. Weak forces like hydrophobic interactions and Van der Waal forces can be safely neglected at nanoscale as they are neglected in bulk solutions.
a) True
b) False
View Answer
Explanation: Forces like hydrophobic interactions, electrostatic forces, Vander Waal forces etc. cannot be neglected at nanoscale. These forces become way more significant in nanostructures than they are in bulk solutions. They govern the behavior of the particles or molecules in nanostructures.
2. Which of the following option is incorrect about transport in nanofluidics?
a) Reduction of transport flux due to repulsion of solutes from the channel walls
b) Steric exclusion in nanochannels
c) Friction between the wall and particles of the fluid causing a reduction in the flow velocity
d) In nanofluidics, transport under the influence of solvent convection, diffusion does not differ from transport in bulk solution
View Answer
Explanation: Transport in nanofluidics is significantly different from the transport in bulk solution. Here, the nanochannels, due to their large surface area to volume ratio, dominate behavior showing some interesting phenomena. These include ion enrichment or depletion, reduced transport flux due to various reasons, friction between channel walls and particles of fluid, pH changes, and ion permselectivity etc.
3. The flow of a fluid in pipe does not depend upon which of the following factors?
a) Density of fluid
b) Gaussian equation
c) Viscosity of fluid
d) Reynolds’s Number
View Answer
Explanation: The fluid flow in a pipe depends on a number of factors. Reynolds’s number is one such factor. It is in turn dependent on the density, viscosity and velocity of the fluid. Also the number and types of bends in pipe, valves and other kinds of fittings affect the flow of fluid.
4. Which of the following statement does not account for the reduction of the transport flux?
a) Exclusion of molecules or particles from liquid layer close to the wall
b) Spring force between particles
c) Friction between the nanochannel walls and particles of the fluid
d) Adsorption of molecules on channel wall material
View Answer
Explanation: There are a number of reasons behind the reduction of transport flux during transport in nanofluidics. These include: (a) Exclusion of molecules or particles from liquid layer close to the nanochannel wall due to steric exclusion, (b) adsorption of molecules on channel wall material, (c) friction of solutes with the channel walls due to proximity of the walls.
5. What is the major drawback of the advanced numerical techniques in nanofluidics?
a) High computational cost
b) Time consuming
c) Poor understanding of atomistic behavior in confined nanoscale transport
d) Very low accuracy and precision
View Answer
Explanation: The advent of advanced numerical techniques in the field of nanofluidics has led to the solution of many critical questions regarding the atomistic behavior governing the nanoscale transports. Moreover, the high accuracy rates and ability to produce quick results have favored their applications in research and development. But one of the major downside to this technique is the huge computational cost which often limits its usage.
6. A number of challenges are associated with fluid flow through nanopipes. Which of the following is not one of them?
a) Coulter counting
b) Clogging of tube
c) Presence of insoluble particles in fluid
d) Presence of macromolecules in the fluid
View Answer
Explanation: There are few challenges in relation to the fluid flow through nanopipes and nanotubes. These include clogging of tubes due to the presence of insoluble debris and macromolecules in the liquid. Large polymers in the liquid may also cause blockage of channels.
7. Choose one option that does not correspond to the advantages of nanofluidics.
a) High surface to volume ratio
b) Lower heat capacity
c) Molecular confinement
d) Presence of macromolecules in fluids
View Answer
Explanation: Nanofluidics is a fast developing branch of nanotechnology studying the behavior and application of fluids in and around structures of 100nm or smaller. Despite facing considerable challenges, the field offers great opportunities for new mechanisms and technologies to manipulate nanoscale objects. This is due to some of its advantageous properties like high surface to volume ratio, molecular confinement and lower heat capacity.
8. Gravitational forces operate at nanoscale.
a) True
b) False
View Answer
Explanation: Gravitational force is the weakest of the four fundamental forces. Though it has insignificant influence at the subatomic level, gravitational attraction holds at nanoscale, for object separations in the range of 0.04 – 4 nms.
9. What is the physical significance of Reynold’s Number?
a) Dimensionless quantity
b) No-slip boundary condition
c) Expresses the relative importance of viscosity and inertia in fluid flow
d) Unit-less quantity
View Answer
Explanation: Reynold’s number is very important in predicting flow type in different fluid flow situations. At lower values of Reynold’s number, viscosity dominates and there is high resistance to flow. Such a flow is stated as laminar flow. While at higher values, inertia is predominant and fluid flow is turbulent.
10. Why do hydrophobic interactions occur between two hydrophobic particles in water?
a) To increase their contact area with water
b) To reduce Vander Waal forces acting between them
c) To reduce the contact area with water
d) To reduce enthalpy of system
View Answer
Explanation: Hydrophobic interactions exist between two or more non-polar molecules, in the presence of water. The molecules stick or fold in a certain way in order to minimize the energetically unfavorable contact area with water. During these interactions the enthalpy also increases due to the breaking of some hydrogen bonds that form the clathrate cage.
More MCQs on Nanofluidics:
Sanfoundry Global Education & Learning Series – Nanotechnology.
To practice all areas of Nanotechnology, here is complete set of 1000+ Multiple Choice Questions and Answers.
If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]
