1. Interfacial defect does not include which of the following defect?
a) Grain boundary
b) Twin boundary
c) Phase boundary
d) Volume defect
Explanation: Interfacial defects are 2 dimensional defects whereas volume defect is 3 dimensional defects. Grain boundary, Twin boundary and Phase boundary are types of interfacial defect
2. What will be the interfacial energy for domain wall?
a) Greatest compared to other interfacial defects
b) Least compared to other interfacial defects
c) Less than external surface but more than other interfacial defects
d) Less than the external surface and grain boundary but more than other interfacial defects
Explanation: Domain wall is the boundary that separates the region having a different direction of magnetization in case of ferromagnetic and ferrimagnetic material. Hence interfacial energy is least in case of a domain. As magnetization energy is less compared to other energies.
3. Which dimension defect are interfacial defects?
a) 2 dimension
b) 1 dimension
c) 3 dimension
d) 4 dimension
Explanation: Interfacial defect are boundary defect that has 2 dimension and normally separate regions of the materials that have different crystal structures and/or crystallographic orientations. These imperfections include external surfaces, grain boundaries, twin boundaries, stacking faults, and phase boundaries
4. Diffusion is the result of:
a) Random motion of particles
b) Concentration gradient
c) Kinetic energy of particles
d) All of the mentioned
Explanation: Particles in all three phases possess some kinetic energy and are constantly under random motion. However, the rate of this movement is proportional to the number of particles available and hence the net direction of diffusion is from higher concentration to lower.
5. Concentration gradient refers to:
a) Change of concentration with respect to time
b) Change of concentration with respect to space
c) Change of concentration with respect to temperature
d) None of the mentioned
Explanation: Net direction of diffusion depends on the concentration of particles in a particular region of space and hence concentration gradient is defined as the rate of change concentration of particles in a given sample with respect to time.
6. Interstitial diffusion is generally faster than diffusion by vacancy mode. This is because:
a) Number of interstitial sites is greater than vacancies
b) Vacancy diffusion requires more energy than interstitial diffusion
c) Interstitial species are smaller than substitution species
d) All of the mentioned
Explanation: At normal conditions probability of occurrence of an adjacent interstitial site is much greater than that of a vacancy. Moreover, the bondings between the host lattice and interstitial atoms are much weaker.
7. As the temperature rises, the rate of vacancy diffusion in metals:
a) increases
b) decreases
c) remains the same
d) may increase or decrease
Explanation: Since more energy is available at higher energy, it is easier to break existing bonds and form additional vacancies.
8. Generally, the metal-to-metal diffusion takes place by vacancy diffusion.
a) True
b) False
Explanation: Interstitial diffusion occurs for smaller impurities like Carbon, Oxygen, Hydrogen etc. For larger species vacancy diffusion is more common
9. Osmosis is different from diffusion as:
a) Diffusion requires semi-permeable membrane
b) Osmosis requires a liquid solvent
c) Osmosis is a form of active transport
d) In osmosis, solute moves from lower concentration to higher
Explanation: Osmosis is a special type of diffusion where an SPM separates two liquid solutions. Solutes cannot pass through the SPM. As more solvent particles are present in dilute solution than the concentrated one, these particles move through SPM from the former to the latter.
10. Rate of solid-state diffusion does not depend on which of the following?
a) Temperature
b) Diffusing species
c) Host solid
d) Gravity
Explanation: Diffusion is the result of a random motion of particles, i.e. their kinetic energy rather than their potential energy. Hence gravity does not effect the rate.