Q. No.The most efficient packing of similar spheres is obtained in
1. the simple cubic system and the body centered cubic system
2. the simple cubic system and the hexagonal close packed system
3. the face centered cubic system and the hexagonal close packed system
4. the body centered cubic system and the face centered cubic system
How many octahedral and tetrahedral holes are present per unit cell in a face centred cubic arrangement of atoms?
(1) 8,4
(2) 1.2
(3) 4.8
(4) 2.1
Choose the correct matching sequence from the possibilities given
| (a) Crystal defect | (i) AB AB AB. . . . type crystal |
| (b) hcp | (ii) Covalent crystal |
| (c) CsCl | (iii) Frenkel |
| (d) Diamond | (iv) Face centered in cube |
| (e) NaCl | (v) Body centered in cube |
| (a) | (b) | (c) | (d) | (e) | |
| (1) | (iii) | (i) | (ii) | (v) | (iv) |
| (2) | (iii) | (i) | (v) | (ii) | (iv) |
| (3) | (iii) | (v) | (i) | (ii) | (iv) |
| (4) | (v) | (iii) | (iv) | (ii) | (i) |
An element (atomic mass = 100 g mole) having BCC structure has unit cell edge 400 . The density of the element is (number of atom bcc(z)=2)
1. 2.144g/cm3
2. 5.2g/cm3
3. 7.289g/cm3
4. 10.376g/cm3
The appearance of color in solid alkali metal halides is generally due to:-
1. Frankel Defect
2. Interstitial Defect
3. F-Centres
4. Schottky Defect
AB crystallizers in a body-centred cubic lattice with edge length a equal to 387 pm. The distance between two oppositely charged ions in the lattice is
1. 250 pm
2. 200 pm
3. 300 pm
4. 335 pm
In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is -
1. AB2
2. A2B3
3. A2B5
4. A2B
Silver metal crystallises in a cubic closest – packed arrangement with the edge of the unit cell having a length a = 407 pm. What is the radius of silver atom.
(1) 143.9 pm
(2) 15.6 pm
(3) 11.59 pm
(4) 13.61 pm
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