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When does Frenkel defect arise? Give reason.

Important Questions on Solid State

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Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

Experimentally it was found that a metal oxide has formula

M_{0.98} O

. Metal M, is present as

M^{2 +}

and

M^{3 +}

in its oxide. Fraction of the metal which exists as

M^{3 +}

would be:

HARD

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

KBr

is doped with

10^{- 5}

mole percent of

{SrBr}_{2}

The number of cationic vacancies in

1 g

KBr

crystal is

10^{14}

. (Round off to the Nearest Integer). [Atomic Mass :

K = 39.1 u, Br = 79.9 u

N_{A} = 6.023 \times 10^{23}]

MEDIUM

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

Experimentally it was found that a metal oxide has formula

M_{0.98} O .

Metal

M

is present as

M^{2 +}

adn

M^{3 +}

in its oxide. Fraction of the metal which exists as

M^{3 +}

would be :

MEDIUM

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

Analysis shows that

FeO

has a non-stoichiometric composition with formula

{Fe}_{0 \cdot 95} O

. Give reason.

HARD

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

ZnO

turns yellow on heating. Why?

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Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

Given below are two statements:
Statement I : Frenkel defects are vacancy as well as interstitial defects.
Statement II : Frenkel defect leads to colour in ionic solids due to presence of F-centres.

Choose the most appropriate answer for the statements from the options given below:

HARD

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

What type of stoichiometric defect is shown by

ZnS

EASY

Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

Examine the defective crystal given below and answer the question that follows:

$A^{+}$	$B^{-}$	$A^{+}$	$B^{-}$	$A^{+}$
$B^{-}$		$B^{-}$	$A^{+}$	$B^{-}$
$A^{+}$	$B^{-}$	$A^{+}$		$A^{+}$
$B^{-}$	$A^{+}$	$B^{-}$	$A^{+}$	$B^{-}$

State if the above defect is stoichiometric or non-stoichiometric. How does this defect affect the density of the crystal? Also, write the term used for this type of defect.

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Chemistry>Physical Chemistry>Solid State>Defects in Crystal Structure

The correct statement among the following, regarding defects in solids is