Q. No.
I. Mg(s)
II. TiO(s)
III. I2(s)
IV. H2O(s)
The insulator among the given examples is -
1. Only I
2. Only II
3. III and IV
4. II, III, and IV
Schottky defect is observed in crystals when:
| 1. | Some cations move from their lattice site to interstitial sites. |
| 2. | Equal number of cations and anions are missing from the lattice. |
| 3. | Some lattice sites are occupied by electrons. |
| 4. | Some impurities are present in the lattice. |
Chargewise p-type semiconductor is -
1. Positive.
2. Neutral.
3. Negative.
4. Depends on the concentration of p impurity.
To get a n-type semiconductor from silicon, it should be doped with a substance with valency -
1. 2
2. 1
3. 3
4. 5
The most efficient packing is present in -
1. HCP and BCC
2. HCP and CCP
3. BCC and CCP
4. BCC and Simple cubic cell
The incorrect statement among the following regarding hexagonal close packing is:
| 1. | The coordination number is 12. |
| 2. | It has 74% packing efficiency. |
| 3. | Tetrahedral voids of the second layer are covered by the spheres of the third layer. |
| 4. | In this arrangement, spheres of the fourth layer are exactly aligned with those of the first layer. |
Same coordination number for cations and anions is present in:
| 1. | Cl- ions form Fcc lattice and Na+ ions occupy all octahedral voids of the unit cell. |
| 2. | Ca2+ ions form Fcc lattice and F- ions occupy all the eight tetrahedral voids of the unit cell. |
| 3. | O2- ions form Fcc lattice and Na+ ions occupy all the eight tetrahedral voids of the unit cell. |
| 4. | S2- ions form Fcc lattice and K+ ions go into alternate tetrahedral voids of the unit cell. |
The coordination number of a square close-packed structure in two dimensions is -
1. 2
2. 3
3. 4
4. 6
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