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Total questions: 20
Worksheet time: 10mins
Schottky defect is observed in crystals when
some cations move from their lattice site to interstitial sites
equal number of cations and anions are missing from the lattice
some lattice sites are occupied by electrons
some imurity is present in the lattice
Frenkel defect is observed in crystals when
some cations move from their lattice site to interstitial sites
equal number of cations and anions are missing from the lattice
some lattice sites are occupied by electrons
some imurity is present in the lattice
Which statement is true about Schottky Defect?
It is observed in compounds having low coordination number
It is usually favoured by a very small difference in the sizes of cation and anion
It increases the density of the crystal lattice
It is a non-stoichiometric point defect
In METAL EXCESS DEFECTS the sites where an electron gets trapped in the anionic vacancy disturbing the ratio of cation to anion is known as
E- CENTRE
F- CENTRE
G- CENTRE
I- CENTRE
The coordination number in NaCl (simple), ZnS (fcc) and CsCl (bcc) is 6, 12 and 8 respectively. The ionic compounds which will be exhibiting Schottky Defect will be
NaCl, ZnS
ZnS, CsCl
NaCl, CsCl
all will exhibit
The only silver halide which can exhibits Schottky as well as Frenkel defect is
AgF
AgCl
AgBr
AgI
When NaCl crystal is doped with MgCl 2 , the nature of defect produced is
Schottky defect
Frenkel defect
Impurity defect
none of the above
Doping of silicon (Si) - a 14th group element with boron (B) - 13th group element leads to formation of
alloy
n type semiconductor
p type semiconductor
insulator
The metal deficiency defect which occurs when the metal can exhibit variable valencies is usually observed in oxides of
alkali metals
alkaline earth metals
transition metals
all of the above
In which of the following spacing between the valence band and conduction band is relatively more and hence is a poor conductor?
Diamond
Silicon
Copper
Brass
Which one of the following statements is wrong ?
The conductivity of metals decreases with increase in temperature
The conductivity of semiconductors increases with increase in temperature
Ionic solids conduct electricity due to presence of ions in molten state
Silicon and Germanium are extrinsic type semiconductors
The transition oxide which resembles copper in its appearance and conductivity is
MnO
FeO
TiO
ReO3
Fe, Co, Ni which are used to make permanent magnets exhibit
Paramagnetism
Ferromagnetism
Ferrimagnetism
Antiferromagnetism
↑ ↑ ↑ ↑ arrangement of electrons describes which type of magnetism ?
diamagnetism
ferromagnetism
ferrimagnetism
antiferromagnetism
Which of the following is antiferromagnetic in nature?
VO
TiO
CrO2
MnO
Fe3O4 which is a mixed oxide of iron also comes under the category of ferrites exhibit which type of magnetism?
diamagnetism
paramagnetism
ferromagnetism
ferrimagnetism
The temperature above which a ferromagnetic substance looses its ferromagnetism is known as
Critical Temperature
Curie Temperature
Magnetic Temperature
Krafts Temperature
Which of the following statements is not true ?
Pairing of electrons cancels their magnetic moment in the diamagnetic substances
Paramangetic substances are weakly attracted by magnetic field
Ferromagnetic substances cannot be magnetised permanently
The domains in antiferromagnetic substances are oppositely oriented with respected to each other
Which substance acts as superconductor at 4 K ?
Hg
Cu
Na
Mg
Oxygen is an example of
diamagnetic substance
paramagnetic substance
ferromagnetic substance
none of these
