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Correct answer is: (B) CsCl type

r⁺/ r = \(\cfrac{180}{187}\)= 0.962 which lies in the range of 

0.732-1.000.

Hence, 

coordination number = 8 i.e., the

structure is CsCl type.

 Electrons and holes produced by defects cause the conduction of electricity by semiconductors.

Correct answer is: (B) band theory

Option : (c) 698 pm

Correct answer: (A) 4×10²⁵

Correct answer is: (C) in solid NaCl, there is no velocity of ions

Correct answer is: (C) molecular

Correct answer is: (A) ionic

Silicon or Gemanium (group – 14) doped with electron deficient impurity (group-13 element like B or Al or Ga) is called p-type semiconductors. Here conductivity is due to positively charged electron holes. 

13-15 group compounds Eg: InSb,AlP,GaAs, 

12-16 group compounds Eg: ZnS,CdS,CdSe,HgTe. 

Silicon or Germanium (group – 14) doped with electron rich impurity (group-15 element like P or As) is called n-type semiconductors. Here conductivity is due to the extra electron or delocalized electron. 

The process of increasing the conductivity of intrinsic semiconductors by adding an appropriate amount of suitable impurity. 

Correct answer is: (B) 6.79 \(\times\)10^-23

Option : (d) 2.6 Å

Correct answer is: (C) unit cell

Correct answer is: (D) K₃₅C₆₀

Correct answer: (B) boron

Correct answer: (B) Schottky

Physical properties show different values when measured along different in crystalline solids.

It is the anion vacancy which contains unpaired electron in non‐stoichiometric compound containing excess of metal ion. 

Attracted by paramagnetic field and these substances are made of atoms or ions with unpaired electrons.

Correct answer is: (D) Exhibit directional properties of the bond.

Ionic crystals exhibit non-directional properties of the bond.

Glass does not have a regular, repeatable molecular structure.

Option : (a) 1 : 1

Correct answer is: (A) 335 pm

Distance between two oppositely charged ions

(r⁺ + r^- ) = \(\cfrac{\sqrt{3}a}{2}\) = 387 \(\times\)\(\cfrac{\sqrt{3}}{2}\) = 335.14 pm

Correct answer is: (B) 4 Na⁺ ions

Correct answer is: (C) octahedral

The constituent particles of a solid have fixed positions and are not free to move i.e., they possess rigidity. That is why they have a definite volume.

Option : (b) CaCl₂

Correct answer is: (D) all of these

Crystal lattice (space lattice) : A regular arrangement of the constituent particles (atoms, ions or molecules) of a crystalline solid having similar environment in three dimensional space is called crystal lattice or space lattice.

Basically unit cells are of two types as follows :

1. Primitive unit cells : The unit cells in which the constituent particles like atoms, ions or molecules are present only at the corners of the unit cell are called primitive unit cells or simple unit cells.

2. Body-centred unit cell : A unit cell in which the constituent particles are present at the corners as well as at its body-centre is called body-centred unit cell.

3. Face-centred unit cell : A unit cell in which the constituent particles are present at the corners as well as at the centre of each face is called face-centred unit cell or cubic close packed (CCP) unit cell.

4. Base-centred unit cell : A unit cell in which the constituent particles are present at the corners as well as at the centres of two opposite faces is called end-centred unit cell.

(1) The constituent particles like atoms, ions or molecules of the crystal can be arranged in seven different ways changing edges (a, b, c) and angles (α, β, γ) and accordingly they form seven systems or types of the crystal.

(2) These seven crystal system are named as : 

(a) Cubic system, 

(b) Tetragonal system 

(c) Orthorhombic system 

(d) Rhombohedral system 

(e) Monoclinic system 

(f) Triclinic system 

(g) Hexagonal system.

1. There are seven crystal systems according to the edges (a. b, c) and angles (α, β, γ).

2. The constituents of the crystal may be present at corners, face centres, body centres, edge centres and voids.

3. By mathematical analysis, it has been proved that only fourteen different kinds of space lattices are possible.

4. Hence there are fourteen different ways of arrangement of the lattice basis.

5. These fourteen lattices of seven crystal systems are called Bravais lattices.

Correct answer is: (B) 14

BThe formula of compound will be AB₂O₄

Explanation:

We all know that oxygen like bigger molecules occupy the lattice points. The effective number of atoms in a CCP unit cell is 8 x 1/8 + 6 x 1/2 = 4 

Also the total number of tetrahedral voids (X is presnt) in CCP is 8 so no. of divalent ions = 8/8 = 1

Number of Octahedral voids (Y is present) are 4 so 1/2 of no. of divalent ion will be 4/2 = 2

Number of oxide = present at corners + at face centre = 8 x 1/8 + 6 x 1/2 = 4

So formula of compound will be AB₂O₄

Correct answer is: (B) 100 pm

Correct answer is: (A) PQ₂

The correct option is (c) AIN.

Formulas for network solids are simple ratios of the component atoms represented by a formula unit like those for ionic compounds.

Some examples of network solids are diamond with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network of SiO₂ units. Graphite and mica group of silicate minerals structurally contains two dimensional sheets covalently bonded within the layer with other bond types holding the layers together whereas glasses are the disordered network solids. They are prepared by rapid cooling of melts so that little time is left for atomic ordering to happen.

Correct answer: (C) Silver chloride

1. Crystalline solid has long range order of regular pattern of arrangement which repeats periodically over entire crystal.

2. Within the given pattern, the arrangements of different atoms or ions or molecules is different in different directions. Hence the properties like refractive indices in the different directions are different.

This shows that the crystalline solids are anisotropic in nature.

Correct answer: (A) covalent bond

(a) vanderwaalsforces

(b) electrostatic

(c) covalent bond

(d) metallic bond 

Isotropy : The ability of amorphous solids to exhibit identical physical properties even though measured in different directions is called isotropy.

Explanation : This property arises because there is no long range order of regular pattern of arrangement in them and hence the arrangement is irregular along all the directions. Therefore the magnitude of any physical property would be identical along all directions.

 Substances show different properties in different direction & the reverse.  

Let the M²⁺ ion in the crystal be x and M³⁺ =0.98 ‐ x 

Since total change on the compound must be zero 

2x + 3(0.098 ‐ x) ‐ z = 0 

X = 0.88 

%of M²⁺ 0.88/0.96*100 = 91.67 

% of M³⁺ = 100 ‐ 91.91.67 = 8.33

n-type semiconductor means conduction is due to the presence of excess of negatively charged electrons. Hence to convert the elements of 14-group into n-type semiconductor it should be doped with group-15 elements.

The defects discussed so far do not disturb the stoichiometry of the crystalline substance is called non-stoichiometric defect.The colour develops because of the presence of electrons in the anionic sites. These electrons absorb energy from the visible part of radiation and get excited.For example, when crystals of NaCl are heated in an atmosphere of sodium vapours, the sodium atoms get deposited on the surface of the crystal and the chloride ions from the crystal diffuse to the surface to form NaCl with the deposited Na atoms. During this process, the Na atoms on the surface lose electrons to form Na+ ions and the released electrons diffuse into the crystal to occupy the vacant anionic sites. These electrons get excited by absorbing energy from the visible light and impart yellow colour to the crystals.

When NaCl crystals are heated in the presence of sodium vapour some chloride ions left the lattice sites and combine with sodium to form NaCl. For this combination sodium atoms lose electrons to form Na+ ions. The released electrons diffuse into crystal to occupy the anion vacancies which are created by Cl^– ions. In this condition the crystal have excess of sodium. The sites occupied by unpaired electrons are called F-centres or colour centres.
F-centre imparts yellow colour to NaCl crystal because they absorb energy from the visible light and get excited.

Ionic crystals are hard because the strong electrostatic forces of attraction are present in between the oppositiely charged ions. They are brittle because ionic bonds are non-directional in nature.

1. Ionic solids have high melting points. 

2. These solids do not conduct electricity, because the ions are fixed in their lattice positions. 

3. They do conduct electricity in molten state (or) when dissolved in water because, the ions are free to move in the molten state or solution.