Physics Questions and Answers – Classification of Metals, Conductors and Semiconductors

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This set of Physics Quiz for IIT JEE Exam focuses on “Classification of Metals, Conductors and Semiconductors”.

1. The manifestation of the band structure in solids is due to which of the following?
a) Heisenberg’s uncertainty principle
b) Pauli’s exclusion principle
c) Bohr’s correspondence principle
d) Boltzmann’s law
View Answer

Answer: b
Explanation: The electronic configuration of atoms and consequently their manifestation of the band structure of solids can be well explained based on Pauli’s exclusion principle.
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2. The energy band gap is maximum in which of the following?
a) Metals
b) Superconductors
c) Insulators
d) Semiconductors
View Answer

Answer: c
Explanation: The bandgap is maximum in insulators. This makes it difficult for electrons to move to the conduction band. This is contrary to metals and superconductors, which has minimum band gaps facilitating the movement of electrons.

3. At absolute zero, Si acts as which of the following?
a) Non-metal
b) Metal
c) Insulator
d) Superconductor
View Answer

Answer: c
Explanation: At absolute zero, the element, silicon (Si) acts as an insulator due to the absence of free electrons in the conduction band. The other options are not valid.
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4. A piece of copper and another of germanium are cooled from room temperature to 77 K. what will impact on the resistance of each of them?
a) Each of these decreases
b) Copper strip increases and that of germanium decreases
c) Copper strip decreases and that of germanium increases
d) Each of these increases
View Answer

Answer: c
Explanation: With the decrease of temperature, the resistance of copper, which is a metallic conductor, will decrease, whereas the resistance of germanium, which is a semiconductor will increase.

5. In semiconductors at room temperature, which of the following is likely to happen?
a) The valence band is partially empty and the conduction band is partially filled
b) The valence band is filled and the conduction band is partially filled
c) The valence band is filled
d) The conduction band is empty
View Answer

Answer: a
Explanation: In semiconductors at room temperature, the valence band is partially empty and the conduction band is partially filled. The other options are not suitable according to the room temperature condition of semiconductors.
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6. At absolute zero temperature, a semiconductor acts as a conductor.
a) True
b) False
View Answer

Answer: b
Explanation: At absolute zero temperature, a semiconductor does act as an insulator. When the electron gains enough energy to participate in conduction, the electron is at a low energy state. Therefore, the semiconductors pretend like an insulator.

7. Which of the following is true regarding insulators?
a) The valence band is partially filled with electrons
b) The conduction band is partially filled with electrons
c) The conduction band is filled with electrons and valence band empty
d) The conduction band is empty and valence band is filled with electrons
View Answer

Answer: a
Explanation: In insulators, the conduction band is empty and the valence band is filled with electrons. The other options do not correspond to the concept of insulators, but rather conductors and semiconductors.
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8. Crystalline solids are which of the following?
a) Anisotropic
b) Isotropic
c) Amorphous
d) Unipotential
View Answer

Answer: a
Explanation: Crystalline solids are anisotropic as they show different physical properties in a different direction. Therefore, they are neither isotropic, amorphous, nor unit potential in nature.

9. Which of the following is an amorphous solid?
a) Glass
b) Diamond
c) Salt
d) Sugar
View Answer

Answer: a
Explanation: Glass is an amorphous solid. It is a non-crystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. The other options are crystalline.
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10. At which temperature, a pure semiconductor behaves slightly as a conductor?
a) Low temperature
b) Room temperature
c) High temperature
d) Supercritical temperature
View Answer

Answer: c
Explanation: A pure semiconductor behaves slightly as a conductor at high temperatures. Their resistivity decreases as temperature increases. Therefore, at high temperatures, semiconductors slightly act as a conductor.

Sanfoundry Global Education & Learning Series – Physics – Class 12.

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