Tag: solid state

Questions Related to solid state

The electrical resistivity of a semiconductor:

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. increases with temperature

  2. decreases with temperature

  3. increases at low temperature and then decreases

  4. does not change with temperature

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Correct Option: B
Explanation:

As the temperature increase the electrons in the valence band get excited and jump into the conduction band and hence the conductance increases and conductance is inversely proportional to resistivity. Hence, resistivity decreases.

Which of the following, when doped into ultrapure germanium, will convert it into a p-type semiconductor?

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. $C$

  2. $As$

  3. $In$

  4. $Na$

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Correct Option: C
Explanation:

When a pure semiconductor is doped with trivalent elemental impurity $p$ type semiconductors are formed

(A) $C\longrightarrow Tetravalent$
(B) $As\longrightarrow Pentavalent$
(C) $Indium$ $(In)\longrightarrow$ $Trivalent$
(D) $Na\longrightarrow$ $Monovalent$
Thus Indium ($In$) will convert ultrapure germanium into p-type semiconductor.

Mercury becomes superconducting at _________.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. 0 K

  2. 4 K

  3. 40 K

  4. 273 K

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Correct Option: B
Explanation:

Super conductors are the substance which provide the conductivity of electricity at different temperatures. Mercury becomes superconducting at 4 K.

Superconductivity may be defined as a phenomenon in which metals, alloys and chemical compounds become perfect conductors with zero resistivity at temperatures approaching __________.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. room temperature

  2. zero temperature

  3. absolute zero

  4. all of these

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Correct Option: C
Explanation:

Superconductivity may be defined as a phenomenon in which metals, alloys and chemical compounds become perfect conductors with zero resistivity at temperatures approaching absolute zero.

For most metals, the transition temperature lies between _________.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. 2 and 5 K

  2. 20 and 50 K

  3. 200 and 250 K

  4. Above 273K

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Correct Option: A
Explanation:

For most metals, the transition temperature lies between 2 and 5 K. The temperature at which a substance starts behaving as super-conductor is called transition temperature.

Which of the following represent(s) true statement(s)?

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. The electrical resistance of metal does not depends upon temperature.

  2. Electrical resistance increases with decrease in temperature.

  3. The electrical resistance becomes almost zero near the absolute temperature.

  4. All of the above

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Correct Option: C
Explanation:

The following represents true statements. The electrical resistance of metal depends upon temperature. Electrical resistance decreases with decrease in temperature. The electrical resistance becomes almost zero near the absolute temperature.

The temperature at which a substance starts behaving as super-conductor is called _________.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. normal temperature

  2. transition temperature

  3. regular temperature

  4. all of these

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Correct Option: B
Explanation:

The temperature at which a substance starts behaving as super-conductor is called transition temperature. For most metals, the transition temperature lies between 2 and 5 K.

superconductors are _________.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. paramagnetic

  2. diamgnetic

  3. both a and b

  4. none of these

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Correct Option: B
Explanation:

Superconductors are diamagnetic.

The highest temperature at which superconductivity has been observed for alloys of niobium $(Nb 3Ge)$ is _______.

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. 4 K

  2. 10 K

  3. 23 K

  4. 47 K

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Correct Option: C
Explanation:

The highest temperature at which superconductivity has been observed is 23 K for alloys of niobium $(Nb _3Ge)$.

In a n-type semiconductor, which of the following statements is true?

chemistry solid state electrical and magnetic properties of solids impurity defects properties of solids

  1. Electrons are majority carriers and trivalent atoms are dopants.

  2. Electrons are minority carriers and pentavalent atoms are dopants.

  3. Holes are minority carriers and pentavalent atoms are dopants.

  4. Holes are majority carriers and trivalent atoms are dopants.

Show answer
Correct Option: C
Explanation:

The n-type semiconductor can be produced  by doping impurity atoms of valence 5 i.e, pentavalent atoms like phosphorous and so electrons are majority charge carriers and Holes are minority charge carriers.

So correct answer is option C.