To know more about solids download BYJU’S – the learning app. 4. of iron is 7.874 g cm-3. Q .1 and Q 2. What type of interactions hold the molecules together in a polar molecular solid? The density of a substance remains unchanged. (ii) Write the term used for this type of defect. Copper crystallizes into an fee lattice with edge length 3.61 X 10-8 cm. (a) What change occurs when AgCl is doped with CdCl2? 2. What type of stoichiometric defect is shown by AgBr and Agl? Answer: 61. (i) Density Thus, formula of this alloy is AuCd3. Define the following: 46. Ans. We would like to show you a description here but the site won’t allow us. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. to Q.71. Select the correct answer and click on the “Finish” buttonCheck your score and answers at the end of the quiz, Visit BYJU’S for all Chemistry related queries and study materials, Your email address will not be published. (Delhi) 2009 Answer: Frenkel defect. Iron has a body-centred cubic unit cell with a cell edge of 286.65 pm. Answer: 86. Answer: (i) Refer Ans. 30. 18. Which point defect in crystals of a solid does not change the density of the solid? Ans. Answer: Four. 41. How many atoms can be assigned to its unit cell if an element forms (i) a body- This defect is generally found in ionic crystals where anion is much larger in size than the cation, e.g., AgBr, ZnS, etc. (i) Write the type of magnetism observed when the magnetic moments are aligned in parallel and anti-parallel directions in unequal numbers. (ii) Conductivity of silicon increases on doping it with phosphorus. Niobium crystallises in body-centred cubic structure. In this case, a vacancy defect is created on its original position and the interstitial defect is experienced at its new position. Point defects are accounted for when the crystallization process occurs at a very fast rate. Frenkel defects are not found in pure alkali metal 92. (ii) Antiferromagnetism: When magnetic moments are aligned in such a way that net magnetic moment is zero, then magnetism is called anti ferromagnetism, e.g. Use this information to calculate Avogadro’s number. Why type of stoichiometric defect is shown by AgCl? 12. Answer: Estimate the radius of lead atom. Answer:When a solid is heated, it can have vacancy defect (Schottky defect). What type of defect can arise when a solid is heated? One common denominator of aging is the accumulation of genetic damage throughout life (Moskalev et al., 2012) (Figure 2A).Moreover, numerous premature aging diseases, such as Werner syndrome and Bloom syndrome, are the consequence of increased DNA damage accumulation (Burtner and Kennedy, 2010), though the relevance of these and other progeroid syndromes to normal aging … Answer: Frenkel defects are shown by AgBr and Agl. Define … ions and that Ca2+ ions are arranged in a fee lattice. 62. Answer: 83. Give an example of the compound which shows this type of defect. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy l/3rd of tetrahedral voids? Answer: It can be increased by adding appropriate amount of suitable impurity. Answer the following questions: They conduct electricity. of P atoms=1 It has a cell edge length of250 pm. Answer: Answer: It is due to different alignment of particles in different directions. (iii) Give an example of the compound which shows this type of defect. Calculate the density of copper. Which point defect in its crystal units alters the density of a solid? 56. If density is 8.55 g cm-3, calculate atomic radius of niobium using its atomic mass 93 u. to Q.76. This is just the overview of point defects in solids. (At Mass of lead = 207 g mol-1 and NA = 6.02 X 1023mol-1 (ii) Write the term used for this type of defect? [Contribution of an atom at the corner per unit cell is 1/8] As there are 6 face centres in a cube and cadmium atoms fit into six face centresof the cube. (ii) n-type semiconductor. 54. (iv)Ferromagnetic substances are used for making permanent magnets. (i) Write the type of magnetism observed when the magnetic moments are oppositely aligned and cancel out each other. Answer: (i) Unit cell: It is the smallest repeated unit in a crystal lattice, e.g. AgCl shows Frenkel defects. An element X (molar mass = 60 g mol-1) has a density of 6.23 g cm-3. (ii) Antiferromagnetism (ii) How is the density of the crystal affected by this defect? This zone is called forbidden zone. anisotropic in nature. Express the relationship between atomic radius(r) and the edge length (a) of the fee unit cell. (iii)Which one of the following is an example of molecular solid: C02 or Si02 48. An alloy of gold and cadmium crystallises with a cubic structure in which gold atoms occupy the corners and cadmium atoms fit into the face centre. 37. That is each face atom is touching the four corner atoms.) diamond. Answer: 43. 31. to Q.61. Answer: Cu+2, 02, Fe-2. Define the following: 8. Answer: (i) Stoichiometric (ii) Frenkel defect Atomic radius of the metal is 125 pm. How may the conductivity of an intrinsic semiconductor be increased? (b) jb-type semiconductor. (ii) Frenkel defect : This defect arises when some of the ions in the lattice occupy interstitial sites leaving lattice sites vacant. Use this information to calculate Avogadro’s number. (a) Why does Li Cl acquire pink colour when heated in Li vapours? to Q.71. (b) What type of semiconductor is produced when silicon is doped with boron? 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What are n-type semiconductors? The well known mineral fluorite is chemically calcium fluoride. iron, cobalt and nickel show ferromagnetism. The density of iron is 7.874 g cm-3. If its density is 2.7 g cm-3, what is the nature of the cubic unit cell? Answer: Metallic solids conduct electricity in solid state through electrons, while ionic solids conduct electricity in molten state or in aqueous solution through ions. 51. Marks: 70. Your email address will not be published. Answer: The introduction of a small amount of impurity in a semiconductor is called doping. Answer the following questions: Write a feature which will distinguish a metallic solid from an ionic solid. Find the training resources you need for all your activities. What types of solids are electrical conductors, malleable and ductile? Account for the following: Answer: Refer Ans. An element with density 10 g cm-3forms a cubic cell with edge length of 3 X 10-8 cm. 69. 40. The Version table provides details related to the release that this issue/RFE will be addressed. (b) What is the distance between Na+and Cl– ions in NaCl crystal if its density is 2.165 g cm-3. Write a point of distinction between a metallic solid and an ionic solid other than metallic lustre. Answer: The density of lead is 11.35 g cm-3 and the metal crystallizes with fee unit cell. We can generate the full lattice by repeatedly moving the unit cell in the direction of its edges by a distance equal to the cell edge. (Given: N. = 6.022 X 1023 mol-1). (ii) Crystal lattice: It is 3-D arrangement of atoms, ions or molecules. Schematic alignments of magnetic moments in antiferromagnetism. (At mass of iron = 55.845 u) NaCl shows this type of defect. (iii) What type of ionic substances show such defect? Calculate the radius of the silver atom. (a)What are intrinsic semiconductors? On heating a crystal of KC1 in potassium vapour, the crystal starts exhibiting Iron has a body-centred cubic unit cell with a cell edge of 286.65 pm. Answer: (i) What type of non-stoichiometric point defect is responsible for the pink colour of LiCl? 89. Define the following? (a) What type of semiconductor is obtained when silicon is doped with boron? General Instructions: 1. (At mass of iron = 55.845 u) The density 36. Ans. (ii) Phosphorus has five electrons, whereas silicon has four, one excess electron becomes free to move which leads to increase in conductivity. 13. Answer: 72. In an insulator, there is a large energy gap between conduction band and valence band. (ii) Density of crystal decreases. (i) Is the above defect stoichiometric or non-stoichiometric? The density of copper metal is 8.95 g cm-3. Its coordination number is 4. Answer: The gap between valence band and conduction band in the case of insulator is very large. Which point defect in crystals of a solid decreases the density of the solid? Name Designation. Q 12 to Q16. The edge of the unit cell is 5.46 X 10-8 cm in lengtli. (ii) What type of stoichiometric defect is shown by NaCl? This process is called doping. Copper crystallises with face-centred cubic unit cell. An element with density 11.2 g cm-3 forms an fee lattice with edge length of 4 X 10-8cm. 9. (i) Metal excess defect. (ii) Crystal lattice and unit cell (ii) It is due to missing of cations and anions from their positions. 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CHEMISTRY CLASS-XII LIST OF MEMBERS WHO REVIEWED AND REVISED SUPPORT MATERIAL OF CHEMISTRY AS PER LATEST SYLLABUS PRESCRIBED BY CBSE FOR CLASS XII (2019-20) S. No. Name the type of crystal defect which is produced when NaCl crystal is doped with MgClj. (ii) Refer Ans. Acquired outcomes will assist as a very imperative landmark in the knowledge of crystal physics. Put your understanding of this concept to test by answering a few MCQs. 82. 29. 3. Answer: (i) Those solids which have 3-D arrangement of atoms, ions or molecules are called crystalline solids, e.g. If the radius of copper atom is 127.8 pm, calculate the density of copper metal. [Contribution per unit cell of an atom at face centre is 1/2.] What is the formula of a compound in which the element ‘Y’ form hep lattice and atoms of ‘X’ occupy 1/3 r“ of octahedral voids. How many atoms constitute one unit cell of a face-centred cubic crystal? 95. a length of 400 pm. 3. In this, the size of cations and anions are of almost the same. NaCl. What is meant by the term ‘forbidden zone’ in reference to band theory of solids? An ionic compound shows the same in Frenkel and Schottky defect. The overall density is not affected by this change. Important Questions for Class 12 Chemistry Chapter 1 The Solid State Class 12 Important Questions The Solid State Class 12 Important Questions Very Short Answer Type Question 1. This kind of vacancy defects is found in Ionic Solids. (iii) Those ionic substances in which cations and anions are of similar size, e.g. 28. Answer: Four. Examine the given defective crystal: Aluminium crystallises in a cubic close-packed structure. Use this information to calculate Avogadro’s number. 4. Formula of compound is PQ. Answer: Refer Ans. Iron(II) oxide has a cubic structure and each side of unit cell is 5 A. Get the latest news and analysis in the stock market today, including national and world stock market news, business news, financial news and more Answer: (ii) Schottky defect. Answer: (a) LiCl when heated with lithium vapours, Li+ become in excess which attract Cl- and the vacant position of anion is occupied by electron forming F-centre which absorbs light from visible region and radiates pink colour. Answer:  Four. What is the formula of compound? Calculate the radius of the silver atom. In this kind of point defect, the ratio of positive and negative ions (Stoichiometric) and electrical neutrality of a solid is not disturbed. (ii) Write the term used for the electron occupied site. [Atomic mass of Fe = 56 u, O = 16 u, NA = 6.023 X 1023 mol-1] Solid State ChemiStry and itS appliCation 2014 Anthony R. West 17. 14. Define paramagnetism with an example. Write a point of distinction between a metallic solid and an ionic solid other than metallic lustre. Answer: Refer Ans. (b) Ferromagnetism An element with density 2.8 g cm-3 forms a fee unit cell with edge length 4 X 10-8 cm. If its density is 2.7 g cm-3, what is the nature of the cubic unit cell? 5. Silver crystallises in face-centred cubic (fee) unit cell. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 2/3rd of tetrahedral voids? Each side of the unit cell has a length of 400 pm. (i) What is the length of the side of the unit cell? Crystalline solids are formed by joining many small crystals. 23. Answer: n-type semiconductor is obtained when silicon is doped with arsenip. Use this information to calculate Avogadro’s number. (i) F-centre (ii) p-type semiconductor (i) Ferromagnetism That is each face atom is touching the four corner atoms.) Fixed: Release in which this issue/RFE has been fixed.The release containing this fix may be available for download as an Early Access Release or a General Availability Release. Answer: Metallic solids are electrical conductors, malleable and ductile. Answer: Schottky defect alters the density of a solid. (iii)C02 is an example of molecular solid. Cation vacancy defect or Non-stoichiometric defect or impurity defects. Answer: Schottky defect decrease the density of the solid. Examine the given defective crystal: (i) Antiferromagnetism Answer: (i) In Schottky defects, large number of cations and anions are missing which lead to lowering in density of crystal lattice. Answer: Ferromagnetic substances would make better permanent magnets. What is the formula of a compound in which the element Y forms ccp lattice and atoms of X occupy 2/3rd of octahedral voids? What is the length of the edge of unit cell? Read About The Imperfections In Solids And Different Types Of Point Defects - Frenkel defect, Stoichiometric Defect, Impurity Defect, Non-Stoichiometric Defect At BYJUS. 42. Answer: 32. Answer: (i) Ferrimagnetism (ii) Schottky defects. Calculate the atomic mass of the element. (i) Primitive unit cell (ii) Schottky defect (iii)Ferromagnetism. 33. definition of - senses, usage, synonyms, thesaurus. If density of the oxide is 4 g cm-3, calculate the number of Fe+2and O-2ions present in each unit cell. AgBr shows Schottky defect also. Thus, 8 gold atoms at the eight corners contribute 8 X 1/8= 1 atom. (iii) Magnetic dipole’s are aligned parallel and antiparallel but unequal in number leading to small magnetic moment. Resolved: Release in which this issue/RFE has been resolved. Answer: Metals are malleable and ductile. 74. in sodium chloride and caesium chloride, the unit cell is a cube. Answer the following questions: Calculate the packing efficiency of a metal crystal for simple cubic lattice. (iii) Ferrimagnetism. These defects mainly happen due to deviation in the arrangement of constituting particles. (iii) When LiCl is heated with lithium vapours, it shows this type of defect. Ans. There is so much to learn about the crystalline solids, its structure and its defects. Roop Narain Chauhan Vice Principal Group Leader (9868373636) R. P. V. V., Sector-19 Dwarka, New Delhi 2. (i) Schottky defect (ii) Frenkel defects (iii) F-centre 10. 90. (iii) Density of crystal decreases. (ii) Frenkel defect. What type of semiconductor is obtained when silicon is doped with arsenic? Silver crystallizes in face-centred cubic unit cell. centred cubic cell, and (ii) a face-centred cubic cell? Answer: 65. Test your Knowledge on Imperfections in solids point defects! Its coordination number is 6. (i) Tetrahedral and octahedral voids close packed layer? Answer: 60. Answer: It means crystalline substances show different optical and electrical properties in different directions, i.e. (Given: NA = 6.022 X 1023 mol-1) If the radius of silver atom is 145 pm, what is the length of each side of the unit cell? If the edge of the unit cell is 316.5 pm, what is the radius of tungsten atom? to Q.10 (i). Unit cell: It is a portion of crystal lattice which on repetition gives crystal lattice. (i) What type of stoichiometric defect is shown by the crystal? 11. to Q.9 (ii). 1. It might seem impossible to you that all custom-written essays, research papers, speeches, book reviews, and other custom task completed by our writers are both of high quality and cheap. (Given: At. Are case based questions and have 4 parts each. Calculate the molar mass if its density is 8.0 g cm-3. Short Answer Type Questions [I] [2 Marks}. Required fields are marked *, Metal excess defect due to anionic vacancies, Metal excess defect due to the presence of extra cations at interstitial sites. to Q.57. 55. to Q. (iii) It is because Ag+ and X- differ appreciably in their size where X represents any halide ion. . What is meant by an ‘intrinsic semiconductor’? What type of stoichiometric defect is shown by AgCl? 22. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. Answer: As there are 8 corners in a cube and gold atoms are present at the corners of the cube. What is the two-dimensional coordination number of a molecule in a square Answer: Refer Ans. Question 2. They have permanent magnetic moment due to unpaired electrons, e.g. CBSE Maths notes, CBSE physics notes, CBSE chemistry notes, Very Short Answer Type Questions [1 Mark]. 64. A non-ionic compound mainly shows vacancy and interstitial defects. An element occurs in bcc structure. 25. AII the questions are compulsory. NaCl and NaBr. Answer: 52. Answer: It is due to loss of electron by potassium atom to form K+ ions which attract Cl- ions and position of Cl~ ions is occupied by electron forming F-centre which absorbs light from visible region and radiates violet colour. (ii) Electrical conductivity Answer: Refer Ans. Ans. Answer: Interstitial defect increases the density of a solid. Answer: 57. 21. It happens when there is a huge difference in the size of anions and cations. 27. (b) No. Answer: AgCl shows Frenkel defect. 49. 20. (ii) Electrical conductivity increases in both Frenkel and Schottky defects. (c) What type of point defect is produced when AgCl is doped with CdCl2? (NA = 6.02 X 1023 atoms mol-1) 26. of Q atoms = 8 x 1/8 = 1, No. Answer: Dipole-dipole interactions, dispersion forces and van der Waals’ forces of attraction hold the molecules together in a polar molecular solid. Silver crystallises in a fee lattice. What is the nature of cubic unit cell if the atomic mass of the element is 81 g mol? (ii) F-centre. (At mass of iron = 55.845 u) (iii) How does this defect affect the density of the crystal? coordination number of central sphere is 8 in body-centred cubic structures. to Q.12 (ii). Are MCQs and carry one mark each. What is this due to? There are 33 questions in this paper. 87. Answer: How many atoms constitute one unit cell of a face-centred cubic crystal? (i) Is the above defect stoichiometric or non-stoichiometric? Identify the type of cubic unit cell, if the edge length of the unit cell is 4 X 10-8cm. Fig. mass of Cu = 63.54 g mol-1 and NA = 6.02 X 1023 mol-1). to Q.12 (iii). 53. Which type of ionic substances show Schottky defect in solids?