PrepBharat

1. A solid with high electrical and thermal conductivity from the following is
a) Si
b) Li
c) NaCl
d) Ice

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2. If we mix a pentavalent impurity in a crystal lattice of germanium, what type of semiconductor formation will occur?
a) p-type
b) n-type
c) both (a) and (b)
d) None of the two

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3. The addition of arsenic to germanium makes the latter a
a) metallic conductor
b) intrinsic semiconductor
c) mixed conductor
d) extrinsic semiconductor

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4. A semiconductor of Ge can be made p-type by adding
a) trivalent impurity
b) tetravalent impurity
c) pentavalent impurity
d) divalent impurity

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5. On doping Ge metal with a little of Ga, one gets
a) p-type semi conductor
b) n-type semi conductor
c) insulator
d) rectifier

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6. The pure crystalline substance on being heated gradually first forms a turbid liquid at constant temperature and still at higher temperature turbidity completely disappears. The behaviour is a characteristic of substance forming.
a) Allotropic crystals
b) Liquid crystals
c) Isomeric crystals
d) Isomorphous crystals

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7.If one end of a piece of a metal is heated the other end becomes hot after some time. This is due to
a) Energised electrons moving to the other part of the metal
b) resistance of the metal
c) mobility of atoms, in the metal
d) minor perturbation in the energy of atoms.

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Answer: a
Explanation:

8. Which of the following is ferroelectric compound?
a) \[BaTiO_{3}\]
b) \[K_{4}\left[Fe \left(CN\right)_{6}\right]\]
c) \[Pb_{2} O_{3}\]
d) None of these

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9. Which of the folliowing metal oxides is anti-ferromagnetic in nature?
a) \[MnO_{2}\]
b) \[TiO_{2}\]
c) \[VO_{2}\]
d) \[CrO_{2}\]

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10. Among the following which compound will show the highest lattice energy?
a) KF
b) NaF
c) CsF
d) RbF

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