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If $NaCl$ crystal has two 'F' centres per unit cell. Then the possible formula per unit cell is

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Important Questions on Solid State

EASY

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

The correct statement regarding defects in solid is

HARD

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

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>Imperfection in Solids

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>Imperfection in Solids

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:

EASY

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

The correct statement regarding defects in crystalline solids is :

MEDIUM

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

Analysis shows that

FeO

has a non-stoichiometric composition with formula

{Fe}_{0 \cdot 95} O

. Give reason.

HARD

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

What type of stoichiometric defect is shown by

ZnS

EASY

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

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.

MEDIUM

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

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

1

) Frenkel defect is favored by small difference in the sizes of cation and anion.

2

) Frenkel defect is a metal excess defect.

3

) Trapping of electron in the lattice leads to formation of F-centres.

4

) Schottky defect has no effect on the physical property of solids.

MEDIUM

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

A metal exists as an oxide with formula

M_{0.96} O

Metal

M

can exist as

M^{+ 2}

and

M^{+ 3}

in its oxide

M_{0.96} O

. The percentage of

M^{+ 3}

in the oxide is, nearly

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Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

Out of $NaCl$ and $AgCl$ , which one shows Frenkel defect and why?

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Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

Schottky defect is shown by

MEDIUM

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

Why is Frenkel defect not found in pure alkali metal halides?

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Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

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:

MEDIUM

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

State whether true of false : In Schottky defect, in order to maintain electro-neutrality, the number of missing cations and anions are equal.

EASY

Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

Give the ‘significance of a ‘lattice point’. Which point does defect increase the density of a crystal?

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Chemistry>Physical Chemistry>Solid State>Imperfection in Solids

What type of defect can arise when solid is heated?

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Chemistry>Physical Chemistry>Solid State>Imperfection in Solids