Tag: nanotechnology

Questions Related to nanotechnology

The size of E-coli bacteria is about :

physics electronic devices nanoscience and nanotechnology nanotechnology logic gates

  1. 500 nm

  2. 1000 nm

  3. 2000 nm

  4. 3000 nm

Show answer
Correct Option: C
Explanation:

Each E-coli bacterium measures 0.5 μm in width by 2 μm in length i.e, 2000 nm.
So option (b) is correct,

Diameter of fullerenes is about :

nanoscience and nanotechnology nanotechnology logic gates

  1. 1 nm

  2. 3 nm

  3. 5 nm

  4. 7 nm

Show answer
Correct Option: A
Explanation:

The van der Waals diameter of a $C _{60}$ molecule is about 1.1 nanometer (nm).

State whether true or false :
Tensile strength of nano-material is greater than that of steel.

nanoscience and nanotechnology nanotechnology logic gates

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Because of its very small size, the nano-material has tensile strength greater than that of steel. 

State whether True or False :
At nanoscale, laws of Newtonian mechanics fail.

nanoscience and nanotechnology nanotechnology logic gates

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Quantum mechanics is required to understand the behavior of nanoscale systems because Newtonian theories collapse and fail at this scale. If Newtonian laws governed the working of atoms, then negatively charged electrons would be attracted to the positively charged nucleus of the atoms and the two would collide, but this does not happen.

State whether true or false :
Nano-materials with same dimensions but with different structure might have different physical properties.

nanoscience and nanotechnology nanotechnology logic gates

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Nano-materials have the dimensions of about 1-100 nanometers, their material properties change significantly. This is the size scale where quantum effects rule the behavior and properties of particles. Properties of materials depend on size and structure of the material. Even if size is same but the structure of the material is different,  physical properties like melting point, electrical conductivity, etc changes.

For nano-structured materials, the surface area to volume ratio is : 

nanoscience and nanotechnology nanotechnology logic gates

  1. large

  2. small

  3. very small

  4. can't say

Show answer
Correct Option: A
Explanation:

Nano-particles have a relatively larger surface area when compared to the same volume of the material.
For example: Consider a sphere of radius r. 

Surface area of sphere $=4\pi r^{2}$
Volume of sphere $=\dfrac{4}{3}\pi r^{3}$ 

It means given volume is divided into smaller piece, the surface area increases. So, we conclude that surface area to volume ratio is very large for nano-particles. Since nano-particles have a very small size, r is small, so the ratio of surface area to volume is very large.

State whether true or false :
Carbon nanobuds has mixed properties of both fullerenes and nanotubes. 

nanoscience and nanotechnology nanotechnology logic gates

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Carbon nanobud is a material that combines carbon nanotubes and spheroid fullerenes, both allotropes of carbon, in the same structure, forming "buds" attached to tubes. Consequently, nanobuds exhibit the properties of both carbon nanotubes and fullerenes.

State whether true or false :
The greater the surface area for the same volume, the lesser would be the reactivity. 

nanoscience and nanotechnology nanotechnology logic gates

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Greater the surface area, greater are the reaction rates.
This is because reaction occurs when particles in gas/liquid collide with the particles in solid. Increasing the surface area of solid increases the chances of collision taking place. So, reaction rate increases as the surface area is increased.

Which of the following methods can be used to obtain nano sized materials ?

nanoscience and nanotechnology nanotechnology logic gates

  1. Ball-mills methods

  2. Inert-gas condensation technique

  3. Wet-chemical technique

  4. All of the above

Show answer
Correct Option: D
Explanation:

Different physical, chemical, biological methods such as ball milling, inert gas condensation, wet chemical methods are used for obtaining nano-sized materials. So answer is (d) All of the above. 

Which of the following element is a major constituent in the conventional sources of energy ?

nanoscience and nanotechnology nanotechnology logic gates

  1. Hydrogen

  2. Oxygen

  3. Carbon

  4. Aluminium

Show answer
Correct Option: C
Explanation:

Conventional sources of energy include coal, petroleum, natural gas, wood etc. Carbon is their main constituent.