Answer: 24. [NA = 6.02 X 1023 mol-1] 90. 87. . (i) Is the above defect stoichiometric or non-stoichiometric? In ionic solids generally, the smaller ion (cation) moves out of its place and occupies an intermolecular space. (b) What type of semiconductor is produced when silicon is doped with boron? Answer: (i) Density remains the same in Frenkel defect, whereas Schottky defect leads to lowering of density. 78. of Q atoms = 8 x 1/8 = 1, No. What is the length of the edge of unit cell? (i) Write the type of magnetism observed when the magnetic moments are oppositely aligned and cancel out each other. Each side of the unit cell has a length of 400 pm. Ans. (ii) Crystal lattice: It is 3-D arrangement of atoms, ions or molecules. (b) A solid with cubic crystal is made of two elements ‘P’ and ‘Q’ Atoms of ‘Q’ are at the comers of the cube and ‘P’ at body centre. Historically, crystal point defects were first regarded in ionic crystals, not in metal crystals that were much simpler. The edge of the unit cell is 5.46 X 10-8 cm in lengtli. 14. (iii) What type of ionic substances show such defect? Cheap paper writing service provides high-quality essays for affordable prices. (iii) Give an example of the compound which shows this type of defect. Formula of compound is PQ. 10. Short Answer Type Questions [I] [2 Marks}. Answer: Answer:When a solid is heated, it can have vacancy defect (Schottky defect). What is meant by an ‘intrinsic semiconductor’? Ans. (i) F-centre (ii) p-type semiconductor 3. 80. (i) What type of stoichiometric defect is shown by the crystal? Answer: It means crystalline substances show different optical and electrical properties in different directions, i.e. What type of defect can arise when a solid is heated? close packed layer? 77. Express the relationship between atomic radius (r) and the edge length (a) in the bcc unit cell. Explain how you can determine the atomic mass of an unknown metal if you know its mass density and the dimensions and type of unit cell of its crystal. (Given: N. = 6.022 X 1023 mol-1). Ans. Roop Narain Chauhan Vice Principal Group Leader (9868373636) R. P. V. V., Sector-19 Dwarka, New Delhi 2. (At mass of iron = 55.845 u) 12. .•. They conduct electricity. Resolved: Release in which this issue/RFE has been resolved. Iron has a body-centred cubic unit cell with a cell edge of286.65 pm. Write a feature which will distinguish a metallic solid from an ionic solid. Schottky defect is however different from frenkel defect wherein the atoms permanently leave the crystal in terms of schottky defect while atoms usually stay within the solid crystal in frenkel defect. Define the following: Ans. Also calculate the radius of an atom of this element. Answer: 68. 53. ‘Crystalline solids are anisotropic in nature.’ What does this statement mean? The overall density is not affected by this change. Ans. Niobium crystallises in body-centred cubic structure. 50. Answer: Refer Ans. 82. Answer: Refer Ans. Answer: 72. (At mass of iron = 55.845 u) Answer: Metallic solids are electrical conductors, malleable and ductile. An element with density 11.2 g cm-3 forms an fee lattice with edge length of 4 X 10-8cm. 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. In this kind of point defect, the ratio of positive and negative ions (Stoichiometric) and electrical neutrality of a solid is not disturbed. [Contribution of an atom at the corner per unit cell is 1/8] (ii) Which stoichiometric defect does not change the density of the crystal? (a) What change occurs when AgCl is doped with CdCl2? There are 33 questions in this paper. Answer: As there are 8 corners in a cube and gold atoms are present at the corners of the cube. The most comprehensive list of manufacturing terms, definitions and Acronyms on the internet Short Answer Type Questions [II] [3 Marksl. Answer: (a) jb-type semiconductor Which point defect in crystals of a solid does not change the density of the solid? Answer: 83. 1. Examine the given defective crystal. The density of iron is 7.874 g cm-3. 4. Answer: The gap between valence band and conduction band in the case of insulator is very large. (i) What type of stoichiometric defect is shown by KC1 and why? Assign formula for this alloy. Write a point of distinction between a metallic solid and an ionic solid other than metallic lustre. What is the length of the side of the unit cell of the metal? If the radius of copper atom is 127.8 pm, is the copper unit cell a simple cubic, a body-centred cubic or a face-centred cubic structure? Define the following: (Assume the atoms just touch each other on the diagonal across the face of the unit cell. An element occurs in bcc structure. Fig. Define the following? Crystalline solids are formed by joining many small crystals. Write a point of distinction between a metallic solid and an ionic solid other than metallic lustre. Answer: Schottky defect decrease the density of the solid. How may the conductivity of an intrinsic semiconductor be increased? Answer: (i) It is stoichiometric defect. 27. [Contribution per unit cell of an atom at face centre is 1/2.] In this, the size of cations and anions are of almost the same. Which type of ionic substances show Schottky defect in solids? How many atoms constitute one unit cell of a face-centred cubic crystal? anisotropic in nature. This kind of vacancy defects is found in Ionic Solids. Which point defect in its crystal [â¦] Answer: (i) Anion vacancies occupied by free electrons as in alkali metal halides. Answer: n-type semiconductor is obtained when silicon is doped with arsenip. (iii) How does this defect affect the density of the crystal? 29. 46. Give an example of the compound which shows this type of defect. coordination number of central sphere is 8 in body-centred cubic structures. to Q.57. Cation vacancy defect or Non-stoichiometric defect or impurity defects. That is each face atom is touching the four corner atoms.) (a) Why does Li Cl acquire pink colour when heated in Li vapours? (i) Z = 2 for bcc element (ii) Z = 4 for fee element. 5. 1. Read About The Imperfections In Solids And Different Types Of Point Defects - Frenkel defect, Stoichiometric Defect, Impurity Defect, Non-Stoichiometric Defect At BYJUS. (i) Schottky defects lower the density of related solids. Name the type of crystal defect which is produced when NaCl crystal is doped with MgClj. (i) Antiferromagnetism Test your Knowledge on Imperfections in solids point defects! Name Designation. Answer: (a) Its conductance increases due to movement of Ag+ ions. What type of stoichiometric defect is shown by AgBr and Agl? When inoculated at peripheral sites, very little viral DNA reaches the ganglion and this viral DNA is rapidly lost from the ganglia ( Da Costa et al., 1999a , Da Costa et al., 1999b ). What is the formula of compound? (At mass of iron = 55.845 u) to Q.12 (iii). Answer: 86. (c) Impurity defects. 89. Calculate the radius of the silver atom. An element with molar mass 27 g mol-1 forms a cubic unit cell with edge length 4.05 X 10-8cm. (iii) When group 14 elements like Si, Ge are doped with group 15 elements like As, Sb, we get n-type semiconductors. (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. If the radius of silver atom is 145 pm, what is the length of each side of the unit cell? Define paramagnetism with an example. Silver crystallizes in face-centred cubic unit cell. Q3 to Q 11. (ii) Write the term used for this type of defect. Aluminium crystallises in a cubic close-packed structure. Answer: (iii) Why do silver halides show this type of defect? What are n-type semiconductors? An element with density 10 g cm-3forms a cubic cell with edge length of 3 X 10-8 cm. Answer: The introduction of a small amount of impurity in a semiconductor is called doping. Answer the following questions: 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: We also have revealed that the generalized Kudrayashov method is an operative contrivance for large class of schemes of Frenkel - Kontorova model. (b) Ferromagnetism [Delhi] (ii) Coordination number: It is the number of atoms surrounding a central metal atom, e.g. (iii) Those ionic substances in which cations and anions are of similar size, e.g. 35. Answer: Refer Ans. What type of substances would make better permanent magnets, Ferromagnetic or Ferrimagnetic? In terms of band theory, what is the difference 67. to Q.9 (ii). 51. mass of Cu = 63.54 g mol-1 and NA = 6.02 X 1023 mol-1). Define the following terms in relation to crystalline solids: Answer: Answer: Refer Ans. The compound CuCl [Formula mass = 99 g mol-1] has FCC structure like ZnS. (i) Crystalline solids (i) Frenkel defects (iii) n-type semiconductor. (i) Write the type of magnetism observed when the magnetic moments are aligned in parallel and anti-parallel directions in unequal numbers. Thus, 6 cadmium atoms at the six faces contribute 6 x 1/2 = 3. 33. 4. If the edge of the unit cell is 316.5 pm, what is the radius of tungsten atom? Answer: Iron has a body-centred cubic unit cell with a cell edge of 286.65 pm. Calculate the radius of the silver atom. (b) What type of magnetism is shown in the following alignment of magnetic moments? Answer: Interstitial defect increases the density of a solid. Why is glass considered a supercooled liquid? 54. (b) jb-type semiconductor. 20. (iv)Ferromagnetic substances are used for making permanent magnets. Click ‘Start Quiz’ to begin! (i) KC1 shows Schottky defects because K+ and Cl- do not differ appreciably in their size. Unit cell: It is a portion of crystal lattice which on repetition gives crystal lattice. 3. (ii) Density of crystal decreases. 17. to Q.71. Silver crystallises in a fee lattice. 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. ‘Crystalline solids are anisotropic in nature.’ What does this statement mean? AgCl shows Frenkel defects. (a) What type of semiconductor is obtained when silicon is doped with boron? The density of a substance remains unchanged. Use this information to calculate Avogadro’s number. 28. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. What is meant by ‘doping’ in a semiconductor? Answer: Refer Ans. Define ⦠The well known mineral fluorite is chemically calcium fluoride. Answer: Metallic solids can conduct electricity due to movement of electrons in solid state, whereas ionic solids conduct electricity in molten state or in aqueous solution only due to the movement of ions. 31. Calculate the atomic mass of the element. It shows that glass can flow, that is why it is called supercooled liquid. Answer: 45. Acquired outcomes will assist as a very imperative landmark in the knowledge of crystal physics. Studyres contains millions of educational documents, questions and answers, notes about the course, tutoring questions, cards and course recommendations that will help you learn and learn. (i) Is the above defect stoichiometric or non-stoichiometric? (i) Primitive unit cell (ii) Schottky defect (iii)Ferromagnetism. 8. General Instructions: 1. If the radius of copper atom is 127.8 pm, calculate the density of copper metal. (ii) Electrical conductivity increases in both Frenkel and Schottky defects. 9. Answer: Frenkel defect. In an insulator, there is a large energy gap between conduction band and valence band. (ii) What type of semiconductor is formed when silicon is doped with As? Give an example of an ionic compound which shows Frenkel defect. Answer: 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. Answer: Refer Ans. It has a cell edge length of250 pm. 15. Why type of stoichiometric defect is shown by AgCl? Answer: Ans. Answer: It is because glass windows are thicker at the bottom and thinner at the top. [Given: Cu = 63.5 g mol-1, NA = 6.022 X 1023mol-1] Answer: 43. 69. Answer: Refer Ans. Give an example. Answer the following questions: 37. To know more about solids download BYJU’S – the learning app. If density of the oxide is 4 g cm-3, calculate the number of Fe+2and O-2ions present in each unit cell. Unresolved: Release in which this issue/RFE will be addressed. (i) The void between three spheres in direct contact and capped by fourth sphere is called tetrahedral void. The density of iron is 7.874 g cm-3. (i) Unit cell (ii) Coordination number centred cubic cell, and (ii) a face-centred cubic cell? Its coordination number is 4. Answer: Four. 7. of iron is 7.874 g cm-3. Answer: Schematic alignments of magnetic moments in ferromagnetism Explain the following terms with suitable examples of each: ‘ Answer: 71. Which point defect in crystals of a solid decreases the density of the solid? That is each face atom is touching the four corner atoms.) Ans. 13. What is this due to? Give one example in each case. Tungsten crystallizes in body-centred cubic unit cell. Use this information to calculate Avogadro’s number. (ii) Frenkel defect. What is the number of atoms in a unit cell of a simple cubic crystal? a length of 400 pm. How many atoms can be assigned to its unit cell if an element forms (i) What is the length of the side of the unit cell? Answer: Answer: AgCl shows Frenkel defect. to Q.61. Estimate the radius of lead atom. Each side of the unit cell has a length of 400 pm. in sodium chloride and caesium chloride, the unit cell is a cube. 47. CBSE Maths notes, CBSE physics notes, CBSE chemistry notes, Very Short Answer Type Questions [1 Mark]. Answer: 57. 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. 34. 41. Answer: The number of atoms in a unit cell of a simple cubic crystal is one [8*1/8=1]. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. Answer: (i) Those solids which have 3-D arrangement of atoms, ions or molecules are called crystalline solids, e.g. 11. Answer: Schottky defect alters the density of a solid. 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. (i) between a conductor and a semiconductor? 52. (i) Schottky defect (ii) Frenkel defects (iii) F-centre 48. How will you distinguish between the following pairs of terms: Examine the given defective crystal: NaCl shows this type of defect. of P atoms=1 Answer: (i) Stoichiometric (ii) Frenkel defect It happens when there is a huge difference in the size of anions and cations. (Upper) Experimental X-ray emission (XES) and X-ray adsorption (XAS) spectra for N adsorbed onto Ni and Cu surfaces.The bonding and antibonding states originating from the adsorbate p xy and p z states and the metal d states are clearly seen. (i) Density This zone is called forbidden zone. (ii) Refer Ans. 93. Which point defect in its crystal units alters the density of a solid? 25. Answer the following questions: Free essays, homework help, flashcards, research papers, book reports, term papers, history, science, politics Are MCQs and carry one mark each. Frenkel defects are not found in pure alkali metal 62. Its coordination number is 6. Answer the following questions: (b) No. As there are 6 face centres in a cube and cadmium atoms fit into six face centresof the cube. Required fields are marked *, Metal excess defect due to anionic vacancies, Metal excess defect due to the presence of extra cations at interstitial sites. 2. (c) What type of point defect is produced when AgCl is doped with CdCl2? [Atomic mass of Na = 23 u, Cl = 35.5 u, Avogadro’s Number = 6.023 X 1023} 26. Answer: (i) Non-stoichiometric 55. (ii) In a conductor, there is overlapping between conduction band and valence band. (ii) Crystal lattice and unit cell Use this information to calculate Avogadro’s number. 14. Silver crystallizes in face-centred cubic unit cell. 92. Answer: (i) In Schottky defects, large number of cations and anions are missing which lead to lowering in density of crystal lattice. Answer: (i) The cell in which particles are at corners only. to Q.12 (ii). If its density is 2.7 g cm-3, what is the nature of the cubic unit cell? An element with molar mass 27 g mol-1 forms a cubic unit cell with edge length 4.05 X 10-8 cm. Answer: 60. a violet colour. Examine the given defective crystal: CLASS-XI SUBJECT- CHEMISTRY . An element X (molar mass = 60 g mol-1) has a density of 6.23 g cm-3. Answer: 65. How are the following properties of crystals affected by Schottky and Frenkel defects? 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. 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We would like to show you a description here but the site wonât allow us. Find the training resources you need for all your activities. Answer: Metals are malleable and ductile. (i) Ferrimagnetism (ii) Schottky defects. 79. Point defects are accounted for when the crystallization process occurs at a very fast rate. (a)What are intrinsic semiconductors? Answer: (i) Schottky defect. It is known that in one unit cell of this mineral there are 4 Ca2+ ions and 8 F–. Answer: 59. Answer: Short Answer Type Questions [I] [2 Marks]. (i) Is the above defect stoichiometric or non-stoichiometric? (iii) Density of crystal decreases. 94. Answer: (i) Stoichiometric (ii) Frenkel defect (iii) It is because Ag+ and X- differ appreciably in their size where X represents any halide ion. Express the relationship between atomic radius(r) and the edge length (a) of the fee unit cell. (Atomic mass of Cu = 63.55 u and Avogadro’s number (NA) = 6.02 X 1023 mol-1) (i) Ferromagnetism They have permanent magnetic moment due to unpaired electrons, e.g. Answer: Four. Answer: Four. 19. (ii) Which stoichiometric defect decreases the density of the crystal? Silver crystallizes in face-centred cubic unit cell. Answer: 70. 30. NaCl and NaBr. 6. Answer: The property due to which substances are attracted towards magnets. An ionic compound shows the same in Frenkel and Schottky defect. (iii) The magnetic moments are permanently aligned in same direction. Account for the following: 91. Aluminium crystallizes in an fee structure. (ii) Si and Ge doped with trivalent atoms creating electron vacancies, +ve hole increases electrical conductance. AII the questions are compulsory. Answer: (i) 2 (ii) 4. What types of solids are electrical conductors, malleable and ductile? What is meant by the term ‘forbidden zone’ in reference to band theory of solids? The surface of the BHA catalyst is also enriched with Reidinger defects, which were formed by the inequivalent substitution of monovalent Na + ion with higher-valence ions like Ba 2+ and composed of a Ba vacancy, an interstitial O, and two Al Frenkel defects.
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