1. In any atom, the potential energy of an orbiting electron is
A. always positive
B. always negative
C. sometime positive, sometime negative
D. numerically less than its kinetic energy
2. Regarding valence band in a solid which statement is false?
A. it represents the energy possessed by the valence electrons
B. it is the highest occupied band
C. it may be empty in some solids
D. it is either completely filled or partially filled
3. Which statement regarding conduction band is false?
A. it is the lowest unfilled energy band
B. it represents the energy of conduction electrons
C. it lies below the valence band
D. it may be eitherempty or partially filled
4. The neighbouring atoms in the crystalline lattice structure of a semiconductor like Ge form ? bonds.
A. ionic
B. covalent
C. metallic
D. molecular
5. Intrinsic semiconductors are those which
A. are available locally
B. are made of the semiconductor material in its purest form
C. have more electrons than holes
D. have zero energy gap
6. In an N-type semiconductor, the position of the Fermi level
A. is lower than the centre of the energy gap
B. is at the centre of the energy gap is higher than the centre of the energy gap
C.(e) can be anywhere depending upon the doping concentration
D. none of these
7. In order to obtain a p-type germanium, the germanium should be doped with a
A. trivalent impurity
B. tetravalent impurity
C. pentavalent impurity
D. any of the above will do
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