Chemistry

The Solid State

Question:

Match the items given in Column I with the items given in Column II.
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Answer:

(i) -> (d); (ii)-> (c); (iii)->(b); (iv) ->(a)
(i) Mg in solid state show electronic conductivity due to presence of free electrons hence, they are known as electronic conductors.
(ii) MgCl2 in molten state show electrolytic conductivity due to presence of electrolytes in molten state.
(iii) Silicon doped with phosphorus contain one extra electron due to which it shows conductivity under the influence of electric field and known as p-type semiconductor.
(iv) Germanium doped with boron contains one hole due to which it shows conductivity under the influence of electric field and known as n-type semiconductor.
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The Solid State

Q 1.

Explain how vacancies are introduced in an ionic solid when a cation of higher valence is added as an impurity in it.

Q 2.

Which of the following represents correct order of conductivity in solids?
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Q 3.

Classify each of the following as being either a p-type or n-type semiconductor :

  1. Ge doped with In
  2. B doped with Si.

Q 4.

Frenkel defect is also known as
(a) stoichiometric defect (b) dislocation defect
(c) impurity defect (d) non-stoichiometric defect

Q 5.

Gold (atomic radius = 0.144 nm) crystallises in a face centred unit cell. What is the length of the side of the unit cell ?

Q 6.

 Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

Q 7.

Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

Q 8.

Why is glass considered a supercooled liquid?

Q 9.

If the radius of the octahedral void is r and radius of the atoms in close-packing is R, derive relation between rand R.

Q 10.

In which of the following arrangements octahedral voids are formed?
(a) hep (b) bcc (c) simple cubic (d) fee

Q 11.

Ferric oxide crystallises in a hexagonal dose- packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.

Q 12.

What type of stoichiometric defect is shown by:
(i)ZnS (ii)AgBr

Q 13.

Niobium crystallises in a body centred cubic structure. If density is 8.55 g cm-3, calculate atomic radius of niobium, using its atomic mass 93u.

Q 14.

Which of the following is not the characteristic of ionic solids?
(a) Very low value of electrical conductivity in the molten state
(b) Brittle nature
(c) Very strong forces of interactions
(d) Anisotropic nature

Q 15.

The number of tetrahedral voids per unit cell in NaCl crystal is
(c) twice the number of octahedral voids
(d) four times the number of octahedral voids

Q 16.

Why does the electrical conductivity of semiconductors increase with rise in temperature?

Q 17.

Assertion (A): Semiconductors are solids with conductivities in the intermediate range from
ncert-exemplar-problems-class-12-chemistry-solid-state-51
Reason (R): Intermediate, conductivity in semiconductor is due to partially filled valence band.

Q 18.

A sample of ferrous oxide has actual formula Fe0.93  O1.00. In this sample, what fraction of metal ions are Fe2+ ions? What is the type of non-stoichiometric defect present in this sample? '

Q 19.

Copper crystallises into a fee lattice with edge length 3.61 x 10-8 cm. Show that the calculated density is in agreement with its measured value of 8.92 gcm-3.

Q 20.

Classify the following as amorphous or crystalline solids: Polyurethane, naphthalene, benzoic acid, Teflon, potassium nitrate, cellophane, polyvinyl chloride, fibreglass, copper

Q 21.

Silver crystallises in fcc lattice. If edge length of the cell is 4.07 x 10-8 cm and density is 10.5 g cm-3, calculate the atomic mass of silver.

Q 22.

A cubic solid is made up of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body centre. What is the formula of the compound? What are the coordination numbers of P and Q?

Q 23.

Cations are present in the interstitial sites in
(a) Frenkel defect (b) Schottky defect
(c) vacancy defect (d) metal deficiency defect .

Q 24.

The total number of tetrahedral voids in the face centered unit cell is
(a) 6 (c) 10
(b) 8 (d) 12

Q 25.

Which of the following is not true about voids formed in three dimensional hexagonal close packed structure?
(a) A tetrahedral void is formed when a sphere of the second layer is present above triangular void in the first layer
(b) All the triangular voids are not covered by the spheres of the second layer
(c) Tetrahedral voids are formed when the triangular voids in the second layer lie above the triangular voids in the first layer and the triangular voids in the first layer and the triangular shapes of these voids do not overlap
(d) Octahedral voids are formed when the triangular voids in the second layer exactly overlap with similar voids in the first layer.

Q 26.

Explain how many portions of an atom located at
(i)corner and (ii)body centre of a cubic unit cell is part of its neighbouring unit cell.

Q 27.

A compound forms hexagonal close-packed. structure. What is the total number of voids in  0. 5 mol of it? How many of these are tetrahedral voids?

Q 28.

Calculate the efficiency of packing in case of a metal crystal for (i) simple cubic, (ii) body centred cubic, and (iii) face centred cubic (with the assumptions that atoms are touching each other).

Q 29.

Copper crystallises into a fee lattice with edge length 3.61 x 10-8 cm. Show that the calculated density is in agreement with its measured value of 8.92 gcm-3.

Q 30.

Which of the following arrangement shows schematic alignment of magnetic moments of antiferromagnetic substances?
ncert-exemplar-problems-class-12-chemistry-solid-state-4

Q 31.

In which of the following structure coordination number for cations and anions in the packed structure will be same?
(a) Cl ions form fee lattice and Na+ ions occupy all octahedral voids of the unit cell.
(b) Ca2+ ions form fee lattice and F- ions occupy all the eight tetrahedral voids of the unit cell
(c) O2- ions form fee lattice and Na+ ions occupy all the eight tetrahedral voids of the unit cell
(d) S2- ions form fee lattice and Zn2+ ions go into alternate tetrahedral voids of the unit cell.

Q 32.

The value of magnetic moment is zero in the case of antiferromagnetic substances because the domains …
(a) get oriented in the direction of the applied magnetic field
(b) get oriented opposite to the direction of the applied magnetic field
(c) are oppositely oriented with respect to each other without the application of magnetic field
(d) cancel out each other's magnetic moment

Q 33.

An excess of potassium ions makes KCl crystals appear violet or Lilac in colour since
(a) some of the anionic sites are occupied by an unpaired electron
(b) some of the anionic sites are occupied by a pair of electrons
(c) there are vacancies at some’anionic sites
(d) F-centres are created which impart colour to the crystals

Q 34.

Why are solids incompressible?

Q 35.

Why does white ZnO (s) become yellow upon heating?

Q 36.

In a compound, nitrogen atoms (N) make cubic close packed lattice and metal atoms (M) occupy one-third of the tetrahedral voids present. Determine the formula of the compound formed by M and N?

Q 37.

Under which situations can an amorphous substance change to crystalline form?

Q 38.

Match the items given in Column I with the items given in Column II.
ncert-exemplar-problems-class-12-chemistry-solid-state-43

Q 39.

 Wh ich of the following lattices has the highest packing efficiency (i) simple cubic (ii) body-centered cubic and (iii) hexagonal close-packed lattice?

Q 40.

Niobium crystallises in a body centred cubic structure. If density is 8.55 g cm-3, calculate atomic radius of niobium, using its atomic mass 93u.

Q 41.

In terms of band theory, what is the difference

  1. between a conductor and an insulator
  2. between a conductor and a semiconductor?

Q 42.

Classify .the following solids in different categories based on the nature of intermolecular forces operating in them: Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide

Q 43.

What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Q 44.

Classify each of the following solids as ionic, metallic, modular, network (covalent) or amorphous:
(i) Tetra phosphorus decoxide (P4O10) (ii) Ammonium phosphate, (NH4)3P04 (iii) SiC (iv) I2 (v) P4  (vii) Graphite (viii), Brass (ix) Rb (x) LiBr (xi) Si

Q 45.

How will you distinguish between the following pairs of terms:
(i) Cubic close packing and hexagonal close packing?
(ii) Crystal lattice and unit cell?
(iii) Tetrahedral void and octahedral void?

Q 46.

Under the influence of electric field, which of the following statements are true about the movement of electrons and holes in a p-type semiconductor?
(a) Electron will move towards the positively charged plate through electron holes
(b) Holes will appear to be moving towards the negatively charged plate
(c) Both electrons and holes appear to move towards the positively charged plate
(d) Movement of electrons is not related to the movement of holes

Q 47.

Amorphous solids can also be called
(a) pseudo solids (b) true solids
(c) super cooled liquids (d) super cooled solids

Q 48.

Why does table salt, NaCl sometimes appear yellow in colour?

Q 49.

Why is FeO(s) not formed in stoichiometric composition?

Q 50.

In the following questions, a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choices.
(a) Assertion and Reason both are correct statements and Reason is the correct explanation for Assertion.
(b) Assertion and Reason both are correct statements but Reason is not the correct explanation for Assertion.
(c) Assertion is correct but Reason is wrong.
(d) Assertion is wrong but Reason is correct.

Assertion (A): The total number of atoms present in a simple cubic unit cell is one.
Reason (R): Simple cubic unit cell has atoms at its comers, each of which is shared between eight adjacent unit cells.