Incorrect statement among the following about amorphous solids is -
| 1. | On heating they may become crystalline at a certain temperature. |
| 2. | They may become crystalline on keeping for a long time. |
| 3. | Amorphous solids can be moulded by heating. |
| 4. | They are anisotropic in nature. |
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. |
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 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.
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. |
A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:
| 1. | All the domains get oriented in the direction of the magnetic field. |
| 2. | All the domains get oriented in the direction opposite to the direction of the magnetic field. |
| 3. | Domains get oriented randomly. |
| 4. | Domains are not affected by the magnetic field. |
The correct order of the packing efficiency in different types of unit cells is-
1. Fcc < Bcc < Simple cubic
2. Fcc > Bcc > Simple cubic
3. Fcc < Bcc > Simple cubic
4. Bcc < Fcc > Simple cubic
Correct statement among the following regarding conductivity in solids is -
1.
2.
3.
4.
Match the defects given in Column I with the statements given in Column II.
| Column I | Column II |
| A. Simple vacancy defect | 1. Shown by non-ionic solids and increases the density of the solid |
| B. Simple interstitial defect | 2. Shown by ionic solids and decreases the density of the solid |
| C. Frenkel defect | 3. Shown by non-ionic solids and decreases the density of the solid |
| D. Schottky defect | 4. Shown by ionic solids and density of the solid remains the same |
Codes
| A | B | C | D | |
| 1. | 3 | 1 | 4 | 2 |
| 2. | 1 | 2 | 3 | 4 |
| 3. | 1 | 4 | 3 | 2 |
| 4. | 4 | 1 | 3 | 2 |