Question 1 : Choose the most correct answer.
1. Molecular solids are
a. crystalline solids
b. amorphous solids
c. ionic solids
d. metallic solids
Answer -: A) crystalline solids
2. Which of the follwong is n-type
a. Pure Si
b. Si doped with As
c. Si doped with Ga
d. Ge doped with In
Answer -: b) si doped with As
3. In Frenkel defect
a. electrical neutrality of the
substance is changed.
b. density of the substance is
c. both cation and anion are missing
d. overall electical neutrality is
Answer -: d) overall electrical neutrality is preserved.
4. In crystal lattice formed by bcc unit
cell the void volume is
a. 68 % b. 74 % c.32 % d. 26 %
Answer -: c ) 32%
5. The coordination number of atoms in
bcc crystal lattice is
a. 2. b. 4 c. 6 d. 8
Answer -: d) 8
6. Which of the following is not
a.Four spheres are involved in the
formation of tetrahedral void.
b. The centres of spheres in octahedral
voids are at the apices of a regular
c.If the number of atoms is N the
number of octahedral voids is 2N.
d. If the number of atoms is N/2, the
number of tetrahedral voids is N.
Answer -: c) if the number of atoms is N the number of octahedral voids is 2N.
7. A compound forms hcp structure.
Number of octahedral and tetrhedral
voids in 0.5 mole of substance is
a. 3.011×1023, 6.022×1023
b. 6.022×1023, 3.011×1023
c. 4.011×1023, 2.011×1023
d. 6.011×1023, 12.022×1023
Answer -: a) 3.011x 1023, 6.022×1023.
8. Pb has fcc structure with edge length
of unit cell 495 pm. Radius of Pb
a. 205 pm b. 185 pm
c. 260 pm d. 175 pm
Answer -: d) 175 pm