In calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion (Ca2+) and fluoride ion (F-) are:
1. 4 and 2
2. 6 and 6
3. 8 and 4
4. 4 and 8
The incorrect statement among the following is -
1. | Density decreases in case of crystals with Schottky's defect. |
2. | NaCl(s) is insulator, silicon is semiconductor, silver is conductor, quartz is piezo electric crystal. |
3. | Frenkel defect is favoured in those ionic compounds in which sizes of cations and anions have large difference. |
4. | \(Fe_{0.98}O\) has non stoichiometric metal excess defect. |
Iron exhibits bcc structure at room temperature. Above 900 °C, it transforms to fcc structure. The ratio of density of iron at room temperature to that at 900 °C is:
(Molar mass and atomic radii of iron remain constant with temperature)
1.
2.
3.
4.
The correct statement regarding defects in a crystalline solid is:
1. | Schottky defects have no effect on the density of crystalline solids. |
2. | Frenkel defects decrease the density of crystalline solids. |
3. | Frenkel defect is a dislocation defect. |
4. | Frenkel defect is found in halides of alkaline metals. |
A given metal crystallizes out with a cubic structure having an edge length of 361 pm. If there are four metal atoms in one unit cell, the radius of one atom is:
1. 40 pm
2. 127 pm
3. 80 pm
4. 108 pm
If a is the length of the side of a cube, the distance between the body-centered atom and one corner atom in the cube will be:
1.
2.
3.
4.
A metal crystallizes with a fcc lattice. The edge of the unit cell is 408 pm. The diameter of the metal atom is:
1. 288 pm
2. 408 pm
3. 144 pm
4. 204 pm