If NaCl is doped with 10-4 mol % of SrCl2, the concentration of cation vacancies will be (NA = 6.023 x 1023 mol-1)
1. 6.023 x 1015 mol-1
2. 6.023 x 1016 mol-1
3. 6.023 x 1017 mol-1
4. 6.023 x 1014 mol-1
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The phenomenon in which polar crystals on heating produce electricity is called:-
1. pyro-electricity
2. piezo-electricity
3. ferro-electricity
4. ferri-electricity
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Metals have conductivity of the order of (ohm-1 cm-1):-
1. 1012
2. 108
3. 102
4. 10-6
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Total volume of atoms present in a face centred cubic unit cell of a metal is ( r is atomic radius):
1. 20/3 r3
2. 24/3 r3
3. 12/3 r3
4. 16/3 r3
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Lithium borohydride (LiBH4), crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are:- a = 6.81 Å , b = 4.43 Å ,c = 7.17 Å. If the molar mass of LiBH4 is
21.76 g mol-1.The density of the crystal is:-
1. 0.668 gcm-3
2. 0.585 gcm2
3. 1.23 gcm-3
4. None of these
Difficulty Level:
The arrangement of X- ions around A+ ion in solid AX is given in the figure (not drawn to scale).
If the radius of X- is 250 pm,the radius of A+ is:
1. 104 pm
2. 125 pm
3. 183 pm
4. 57 pm
Difficulty Level:
In an f.c.c. unit cell. atoms are numbered as shown below.The atoms not touching each other are (Atom numbered 3 is face centre of front face).
1. 3&4
2. 1&3
3. 1&2
4. 2&4
Difficulty Level:
A solid has a bcc structure. If the distance of closest approach between the two atoms is 1.73Å . The edge length of the cell is:
1. 200pm
2. pm
3. 142.2 pm
4. pm
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Which is covalent solid?
1. Fe2O3
2. Diamond
3. Graphite
4. All of these
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What type of crystal defects is indicated in the diagram given below?
1. Frenkel and Schottky defects
2. Schottky defect
3. Interstitial defect
4. Frenkel defect
Difficulty Level: