This set of Ceramics Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Electron Energy Bands”.
1. When a number of atoms are brought together, any two electrons cannot have same set of four quantum numbers. This is called _______
a) Pauli Exclusion Principle
b) Valence bond theory
c) Induction theory
d) Von Moses Criterion
View Answer
Explanation: Pauli Exclusion Principle states that any two electrons cannot have same set of four quantum numbers. Electrons can occupy same region in space called orbitals. If two electrons in same orbital have all the four quantum numbers same, it causes instability. Pauli Exclusion Principle proves it.
2. How many molecular orbitals are present in a solid?
a) 0
b) 1
c) 2
d) Infinitely many
View Answer
Explanation: Molecular orbitals are regions in space where probability of finding an electron is the most. By Heisenberg Uncertainty Principle, the electron can be found anywhere in the spatial arrangement of atom as they have very high velocity. That is why, infinitely many molecular orbitals are considered.
3. Which orbital is the highest occupied molecular orbital in diamond?
a) σ*
b) σb
c) ᴨ*
d) ᴨ
View Answer
Explanation: Molecular orbitals are formed by combining atomic orbitals on the atoms in the molecule. The electrons require less energy to excite to molecular orbital σb. Hence, it is highest occupied molecular orbital in diamond.
4. Which orbital is the least occupied molecular orbital in diamond?
a) σ*
b) σb
c) ᴨ*
d) ᴨ
View Answer
Explanation: The electrons require a lot of energy to excite to molecular orbital σ*. Therefore, it is the least occupied molecular orbital.
5. What is the highest filled electron energy band at ground state called?
a) Forbidden region
b) High potential region
c) Valence band
d) Conduction band
View Answer
Explanation: Valence band is the highest filled electron energy band at ground state as there is negligible energy to excite electron to other energy bands. Conduction band starts filling up when electron are under thermal agitation or electric field.
6. Which energy level separates empty and occupied energy levels at ground state?
a) High potential region
b) Fermi energy
c) Valence band
d) Conduction band
View Answer
Explanation: Fermi energy is energy that separates highest and lowest occupied states in a quantum system. It is the maximum kinetic energy an electron can have at 0K. Valence band and conduction band are lowest and highest occupied states respectively.
7. The valence and conduction bands are overlapped in ceramics.
a) True
b) False
View Answer
Explanation: Ceramics are usually bad conductors of electricity. Electrons cannot be excited to conduction band from valence band due to wide forbidden gap. If the valence band and conduction band are overlapped, the material will conduct electricity without requiring lot of energy to excite electrons.
8. Which function does the graph represent?
a) Fermi function
b) Frank reed source
c) Density of states
d) Electron distribution function
View Answer
Explanation: The given graph represents density of states function. It defines number of energy states available to electrons.
9. Which function does this graph show?
a) Fermi function
b) Electron distribution function
c) Density of states
d) Dipole-dipole interaction
View Answer
Explanation: The given graph is of Fermi function. It shows probability of finding an electron at a certain energy state.
10. Density of states in band gap is ______
a) 0
b) 1
c) 2
d) Infinity
View Answer
Explanation: There are no available energy states in band gap. Electrons cannot be excited to band gap. Therefore, density of states in band gap is 0.
Sanfoundry Global Education & Learning Series – Ceramics Engineering.
To practice all areas of Ceramics Engineering, here is complete set of Multiple Choice Questions and Answers.
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