Solid State(12th Grade > Chemistry ) Questions and answers for exam Preparation

Question 1. In AgBr crystal, the ion size lies in the order

A g^{+} << B r^{-}

. On the basis of the given information only, the AgBr crystal should have the following characteristics

Defectless (perfect) crystal
Schottky defect only
Frenkel defect only
Both Schottky and Frenkel defects

Explanation:-

Answer: Option C. -> Frenkel defect only
:
C
AgBr exhibits Frenkel defect due to large difference in the size of

A g^{+} a n d B r^{-}

ions.

Question 2. If the value of ionic radius ratio

(\frac{r_{c}}{r_{a}})

is 0.52 in an ionic compound, the geometrical arrangement of ions in crystal is

Tetrahedral
Planar
Octahedral
Pyramidal

Explanation:-

Answer: Option C. -> Octahedral
:
C
The value of ionic radius ratio is 0.52 which is between 0.414 – 0.732 then the geometrical arrangement of ions in crystal is octahedral.

Question 3. Ferrous oxide has a cubic structure and each edge of the unit cell is 5.0 .
Assuming density of the oxide as

, then the number of

ions present in each unit cell will be
[MP PET 2000]

Four and four
Two and four
Four and two
Three and three

Explanation:-

Answer: Option A. -> Four and four
:
A
Let the units of ferrous oxide in a unit cell =n, molecular weight of ferrous oxide

Ferrous Oxide Has A Cubic Structure And Each Edge Of The Uni...

Question 4. Which of the following is not a characteristic properties of a solid state?

Definite shape
Incompressible
Large intermolecular distances
Fixed positions of the constituent particles

Explanation:-

Answer: Option C. -> Large intermolecular distances
:
C
Following are the characteristic features of a solid state:
I.Definite shape, volume and mass
II.Intermolecular distances are short and intermolecular forces are strong
III.They are incompressible and rigid
IV.The constituent particles have fixed positions and can oscillate only about their mean positions

Question 5. If NaCl is doped with

10^{- 3} m o l

%

S r C l_{2}

, then the concentration of cation vacancies will be

1×10−3mol%
2×10−3mol%
3×10−3mol%
4×10−3mol%

Explanation:-

Answer: Option A. -> 1×10−3mol%
:
A
Each

S r^{2} +

ion introduces one cation vacancy

\Rightarrow

number of cation vacancies = % mole of

S r^{2 +} = 10^{- 3} m o l

%

Question 6. The number of atoms in 100 g of an FCC crystal with density d=10 g/cm³ and cell edge equal to 100 pm is equal to

Explanation:-

Answer: Option A. -> 1×10−3mol%
:
A

The Number Of Atoms In 100 G of An FCC Crystal With Density...

Question 7. A solid is made of two elements X and Z. The atoms Z are in CCP arrangement while the atom X occupy two-third of the tetrahedral sites. What is the formula of the compound?

XZ
XZ2
X4Z3
X2Z3

Explanation:-

Answer: Option C. -> X4Z3
:
C
Tetrahedral sites are double compared to octahedral sites; and X is present in two-third of them
a) So, ratio of X and Z equals

2 \times (\frac{2}{3}) : 1 = 4 : 3

\Rightarrow

formula of the compound =

X_{4} Z_{3}

Question 8. In a solid lattice, cation and an anion both have left lattice site. The lattice defect is known as

intertial defect
valency defect
Frenkel defect
Schottky defect

Explanation:-

Answer: Option D. -> Schottky defect
:
D
It is stoichiometric imperfection, Crystals having ratio of radius of cation to anion is high

Question 9. Doping of silicon (Si) with Arsenic (As) leads to

n-type semiconductor
p-type semiconductor
Metal
Insulator

Explanation:-

Answer: Option A. -> n-type semiconductor
:
A
Arsenic has 5 valence electrons; 4 of them take part in covalent bond formation and the remaining one gets delocalized. This gives rise to an electron-rich impurity or n-type semiconductor.

Question 10. Hexagonal close packed arrangement of ions is described as

ABC ABA
ABC ABC
ABABA
ABBAB

Explanation:-

Answer: Option C. -> ABABA
:
C
ABAB…… is hexagonal close packing