Solid State Questions and Answers

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Solid State Questions and Answers| Class 12th Chapter 1 Solid state Questions and answer| NCERT based|CBSE based

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Solid State Questions and Answers

Q 1. Difference between Schottky and Frenkel defect.

  Scotty defect

It is due to equal number of cations and anions missing from the lattice site. This results in the decrease in density of crystal. This type of defect is found in highly ionic compound with high coordination   number, example NaCl, CaCl, AgBr, etc.

Frenkel defect

It is due to the missing of anions usually cation from the letters sites and they occupy the interstitial sites. It has no effect on the density of crystal. This type of defect is found in crystals, where the difference in the size of cations and anions is very large, example AgCl, AgBr, ZnS, etc.

Q 2. Why zinc oxide is white but becomes yellow on heating?

Ans.  Zinc oxide on heating becomes yellow due to metal excess defect caused by the loss of oxide ions.

Q.3 Why is Frenkel defect found in AgCl.?

Ans.  Frenkel defect is shown by substance where there is large difference in the size of ions. In case of AgCl, there is a large difference in the size of Ag and Cl ions.Hence, AgCl shows frenkel defect. AG+ ion are dislocated from the normal position and are located at interstitial sites.

Q 4. Explain conduction of electricity in metals.

Ans.  A conductor may conduct electricity through moment of electron or ions. Metallic conductor conduct electricity through electrons whereas, electrolytic conductors conduct electricity due to movement of ions under applied electric field. Metals conduct electricity in solid as well as in fusion state. The conductivity of metals depends upon the number of valence electron available per atom. The atomic orbitals form molecular orbitals which are so close in energy to each other as to form a band. If this band is partially filled or it overlaps with a higher energy on occupied orbital, called the conduction band, the electron can flow easily under an applied electric field and the metal shows conductivity example sodium, silver, etc.

Q 5. Explain conduction of electricity in semiconductors?

Ans.  In the case of semiconductors, the gap between the valence band and conduction band is small. Therefore, some electrons may jump from valence band to conduction band and show some conductivity, example silicon, germanium.

Q.6 What are n-type semiconductors?

Ans.  When negatively charged electrons are responsible for the conductivity of semiconductor, it is called n-type semiconductor. Search semiconductors are prepared by doping silicon or germanium with elements of 15 group like P or As.

Q 7. What is doping in semiconductors?

Ans.  Doping is the process of increasing the conductivity of the intrinsic semiconductors by adding suitable impurity.

Q 8. Which type of substances exhibit anti-ferromagnetism?

Ans.  Substances like MnO, MnO2   show anti- ferromagnetism. Their domains are oppositely oriented and cancel out each other’s magnetic moment.

Q 9. What type of substance would make better magnets, ferromagnetic or ferromagnetic?

Ans.  Ferromagnetic substance would make batter magnets because when ferromagnetic substance is placed in magnetic field, all he domains get oriented in the direction of the magnetic field and strong magnetic effect is produced, e.g. Co, Ni and CrO2.

Solid State Questions and Answers
Magnetic moment in ferromagnetic  substance

 

 

But when ferrimagnetic  substance is placed in magnetic field, the domains in the substance are aligned in parallel and antiparallel direction in unequal number. They are weakly attracted by magnetic field as compared to ferromagnetic substance, e.g. FeO4, MgFe24.

 

Solid State Questions and Answers
Magnetic moment in ferrimagnetic substance

Q 10. What is a semiconductor? Describe the two main types of semiconductors and explain mechanism for their conduction.

Ans.  In semiconductors, the gap between the valance and conduction bands is small. Therefore, some electrons may jump to conduction band and show some conductivity of semiconductors increases with rise in temperature. These are the solids with conductivities in the intermediate range from 10-6 to 104 ohm-1m-1.

Q 11. Which types of solids have definite enthalpy of fusion?

Ans.  Crystal solids have definite enthalpy of fusion.

Q 12. Which type of solids have sharp melting points?

Ans.  Crystalline solids have sharp melting points.

Q 13. Distinguish between tetrahedral and octahedral voids.

Ans.  Tetrahedral voids– These are surrounded by four spheres which lie at the vertices if a regular tetrahedron. There are 2 tetrahedral voids per atom in a crystal.

Octahedral voids– There are surrounded by a combination of two triangular voids of the first and second layer. There is one octahedral void per atom in a crystal.

Q 14. Distinguish between crystal lattice and unit cell.

Ans.  Crystal lattice– This is the three dimensional arrangement of constituent particles each particle is depicted as point in the space which represents how the constituent particles are arranged in a crystal.

Unit cell– This is the smallest portion of a crystal lattice which, when repeated in different  direction, generates the entire lattice.

Q 15. Why is glass considered as a supercooled liquid?

Ans.   Glass is an amorphous solid, it has a tendency to flow, though slowly. Hence, it                  called supercooled liquid.

Q 16. How stability of a crystal is related to the magnitude of its melting point?

Ans.   Melting point of a solid is related to the attraction force between its molecules.                    Higher the melting point of a crystalline substance, greater is the forces between                the constituent particles and hence, greater is the stability.

Q 17. Write a distinguishing feature between a metallic solid and an ionic solid.

Ans.   In Solid state, ionic solids are the electrical insulators because ions are not free to              move, e.g. CuSO­­4, NaCl, etc. While metals are good electrical conductors in solid              state because of the presence of free electors, e.g. copper, iron, etc.

Q 18. Why are solids rigid?

Ans.  Solids are rigid due to strong force of attraction between the particles.

Q 19. Why do solids have a definite volume?

Ans. Solids have low thermal energy and high intermolecular forces of attraction,                      therefore  they cannot move, i.e. occupy fixed position and hence they have a                    definite  volume.

Q 20. Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show cleavage property?

Ans.  Solid is amorphous in nature because it shows isotropy, i.e. sane optical properties or same value of refractive index in all directions. It does not show cleavage property, i.e. it gives irregular shape or cleavage.

Q 21. Classify the following as amorphous or crystalline solids:

Polyurethane, naphthalene, benzoic acid, Teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Crystalline solids– benzoic acid, naphthalene, potassium nitrate and copper

Amorphous solids– polyurethane, Teflon, cellophane, polyvinyl chloride and fibre galss.

Q 22. 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.

Ans.  Ionic solids: potassium sulphate and zinc sulphide.

         Metallic solids: tin and rubidium.

         Molecular solids: benzene, urea, ammonia, water and argon.

         Covalent solids: graphite and silicon carbide.

Q 22. Solids A is a very hard electrical insulator in solids as well as in molten state and melts at extremely high temperature. What type of solids is it?

Ans.  ‘A’ is a covalent or network solid because it does not conduct electricity even in                   molten state.

Q 23. What type of solids are electrical conductors, malleable and ductile?

Ans.  Metallic solids are electrical conductors, malleable and ductile.

Q 24. Name the parameters that characterize a unit cell.

Ans.  (a)  Axial distances or edge lengths and (b) axial angles.

Q 25. Give the significance of a ‘lattice point’.

Ans.  Lattice point represents one constituent particles.

Q 26. What is the two dimensional coordination number of a molecule is square close-packed layer?

Ans.  Four.

Q 27. Which of the following lattices has the highest packing efficiency

(i) Simple cubic (ii) body-centred cubic and (iii) hexagonal close-packed lattice?

Ans.  The packing efficiency of hexagonal closed-packed lattice is 74%, body-centred is               68% and simple cubic is 52.4%. Therefore, hexagonal close-packed lattice has the             highest packing efficiency.

Q 28. What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Ans.  Vacancy defect arises when a solid is heated. This results in decrease in density of             crystal lattice.

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Hi there! Such a good article, thank you!