Q. No.
AgBr(s) crystals shows the following defect/s
I. Schottky defect
II. Frenkel defect
III. Metal excess defect
IV Metal deficiency defect
1. I and II
2. III and IV
3. I and III
4. II and IV
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 percentage of empty space in a body centred cubic arrangement is ......... .
1. 74
2. 68
3. 32
4. 26
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
Doping causes-
1. Dislocation defect.
2. Schottky defect.
3. Frenkel defect.
4. Electronic defect.
Silicon doped with electron rich impurity forms -
1. p-type semiconductor.
2. n-type semiconductor.
3. Intrinsic semiconductor.
4. Insulator.
The incorrect statement among the following is:
| 1. | Paramagnetic substances are weakly attracted by magnetic field. |
| 2. | Ferromagnetic substances cannot be magnetised permanently. |
| 3. | The domains in antiferromagnetic substances are oppositely oriented with respect to each other. |
| 4. | Pairing of electrons cancels their magnetic moment in the diamagnetic substances. |
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