CBSE
Multiple Choice QuestionsIf oxide ions are arranged in hep and the aluminium ions occupy two thirds of octahedral voids. What will be the formula of the compound?
AlO3
Al2O3
(Al2O3)2
Al3O4
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 (assuming molar mass and atomic radii of iron remains constant with temperature) is
1/2
If NaCl is doped with 10-4 mol% of SrCl2 the concentration of cation vacancies will be
(NA = 6.02 x 1023 mol-1):
6.02 x 1015 mol-1
6.02 x 1016 mol-1
6.02 x 1017
6.02 x 1017
A solid AB has a NaCl structure. If the radius of cation A+ is 170 pm, then the maximum possible radius of the anion B- is
397.4 pm
347.9 pm
210.9 pm
410.6 pm
Percentage of free space in a body centre cubic unit cell is
30%
32%
34%
28%
The appearance of colour is solid alkali metal halides is generally due to:
F- centres
Schottky defect
Frenkel defect
Frenkel defect
Ferrous oxide has a cubic structure. The length of edge of the unit cell is 5 Å and the density of the oxide is 4 .0 g cm-3 Then the number of Fe2+ and O2- ions present in each unit cell will be
four Fe2+ and two O2-
four Fe2+ and four O2-
two Fe2+ and four O2-
two Fe2+ and two O2-
The fraction of totoal volume occupied by the atoms present in a simple cube is:
π/6
CsBr crystallises in a body centred cubic lattice. The unit cell length is 436.6 pm. Given that the atomic mass of Cs - 133 and that of Br = 80 amu and Avogadro number being
6.02 x 1023 mol-1, the density of CsBr is:
42.5 g/cm3
0.425 g/cm3
8.25 g/cm3
8.25 g/cm3
Which is the incorrect statement?
FeO0.98 has non stoichiometric metal deficiency defect
Density decreases in case of crystals with Schottky's defect
NaCl(s) is insulator, silicon is semiconductor,silver is conductor, quartz is piezo electric crystal
NaCl(s) is insulator, silicon is semiconductor,silver is conductor, quartz is piezo electric crystal
