1. In terms of which of the following properties, metals are better than ceramics?
d) Yield Strength
Explanation: Generally ceramics have equal or better hardness, toughness and yield strength but are highly susceptible to plastic deformation. Even a small stress beyond their yield point leads to fracture.
2. Steels mainly contain iron and carbon. Under which of the following categories do they belong?
a) Metallic Solid
Explanation: Since steels have very small amounts of carbon (usually less than 6%), they are considered iron alloy; hence metallic solid.
3. GFRP is an important composite. It stands for
a) Gelatin Fibre Reinforced Polymer
b) Graphite Fibre Reinforced Polymer
c) Germanium Fibre Reinforced Polymer
d) Glass Fibre Reinforced Polymer
Explanation: Glass Fibre Reinforced Polymer (GFRP) or commonly called fiberglass is a lightweight, high-strength, and corrosion-resistant industrial material.
4. Ceramics make excellent refractory materials. A material is said to be refractory if it:
a) resists the flow of electric current
b) has high refractive index
c) retains its strength at high temperatures
d) all of the mentioned
Explanation: Ceramics, which mainly consist of oxides, carbides and nitrides, can withstand very high temperatures; furnaces are generally lined with such ceramics.
5. Which of the following cannot be used as bio-materials?
d) None of the mentioned
Explanation: Bio-materials are implanted into living bodies for replacement of damaged parts and hence, must be compatible with the body tissues and be non-toxic. As long as these criteria are met, all of the above materials – metals, ceramics, polymers and their combinations can be used as bio-materials.
6. Which of the following is true for polymers?
a) They have very high molecular mass
b) They do not have a linear stress-strain curve
c) They have high strength to mass ratio
d) All of the mentioned
Explanation: Polymeric molecules are aggregates of a large number of monomer units and possess high molecular mass. Hooke’s law generally does not apply to polymers as the stress developed is not directly proportional to deformation. Due to low densities, strength to mass ratio of polymers is often comparable to metals and ceramics.
7. Various isotopes of a given element have same:
a) Number of protons
b) Number of neutrons
c) Molar mass
d) Thermodynamic stability
Explanation: Isotopes of a given element have the same number of protons but not of neutrons which causes variation in molar mass. This also results in different p-n ratio, thus making one isotope more stable than other. For example, protium is stable but tritium is radioactive.
8. Calcium is an isobar of Argon. They differ in:
a) Atomic weight
b) Number of nucleons
c) Number of neutrons
d) None of the mentioned
Explanation: Isobars differ in a number of protons as well as that of neutrons but total number of nucleons( protons and neutrons) is the same for all the isobars. Hence, isobars have the same atomic weight.
9. Species with the same number of neutrons but the different number of protons are called:
Explanation: Isotones are atoms of different elements having the same number of neutrons but different atomic and mass numbers. For e.g., Boron-12 and Carbon-12 are isotones each having 7 neutrons.
10. Atomic number of a species is the number of:
c) Valence electrons
Explanation: Atomic number or the number of protons is the property that differentiates atoms of one species from another. For e.g., atomic numbers of Hydrogen and Helium are 1 and 2 respectively.