A given metal crystallises out with a cubic structure having edge length of 361 pm. If there are four metal atoms in one unit cell, what is the radius of one atom?
The correct statement regarding defects in crystalline solids is
A
Frenkel defects decrease the density of crystalline solids
B
Frenkel defect is a dislocation defect
C
Frenkel defect is found in halides of alkaline metals
D
Schottky defects have no effect on the density of crystalline solids.
Explanation
Frenkel defect is a dislocation defect as
smaller ions (usually cations) are dislocated from
normal sites to interstitial sites. Frenkel defect is
shown by compounds having large difference in the
size of cations and anions hence, alkali metal halides
do not show Frenkel defect. Also, Schottky defect
decreases the density of crystal while Frenkel defect
has no effect on the density of crystal.
3
MCQ (Single Correct Answer)
AIPMT 2015
The vacant space in bcc lattice unit cell is
A
48%
B
23%
C
32%
D
26%
Explanation
Packing efficiency of bcc lattice = 68%
Hence, empty space = 32%.
4
MCQ (Single Correct Answer)
AIPMT 2014
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
A
$${2 \over {\sqrt 3 }}a$$
B
$${4 \over {\sqrt 3 }}a$$
C
$${{\sqrt 3 } \over 4}a$$
D
$${{\sqrt 3 } \over 2}a$$
Explanation
The distance between the
body centered atom and one corner
atom is $${{\sqrt 3 } \over 2}a$$.
Questions Asked from Solid State
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