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.
Difficulty Level:
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
Difficulty Level:
Lithium borohydride (LiBH4), crystallizes 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. 0.67 g cm-3
2. 0.58 g cm-3
3. 1.23 g cm-3
4. None of the above.
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
Difficulty Level:
Which is covalent solid?
1. Silicate
2. Diamond
3. Graphite
4. All of these
Difficulty Level:
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:
The anions (A) form hexagonal closest packing and atoms (C) occupy only 2/3 of octahedral voids in
it. The general formula of the compound is-
1. CA
2. CA2
3. C2A3
4. C3A2
Difficulty Level: