Which of the following arrangements shows the schematic alignment of magnetic moments of antiferromagnetic substances?
1.
2.
3.
4.
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.