CBSE Guess Paper Chemsitry Class XII 2009

Guess Paper – 2009
Class – XII
Subject –Chemistry : Solid State

(Q.1) The appearance of colour in solid alkali metal halides is generally due to: ( 1 mark )
(a) Frenkel defect(b) Interstitial positions(c) F-centres(d) Schottky effect

(Q.2) Schottky defects in crystal is observed when ( 1 mark )

(a) unequal number of cations and anions aremissing from the lattice(b) equal number of cations and anions are missing from the lattice(c) an ion leaves its normal siteand occupies an interstitial site(d) density of the crystal is increased

(Q.3) In an antiflourite structure, cations occupy: ( 1 mark )
(a) Octahedral voids(b) Centre of the cube(c) Tetrahedral voids(d) Corners of the cube

(Q.4) A p-typesemiconductor is electrically ( 1 mark )
(a) Negative(b) Positive(c) Neutral(d) Depends upon the concentration of impurities

(Q.5) Ferrimagnetism is shown by ( 1 mark )
(a) Nickel(b) Oxygen molecule(c) Cromium oxide (CrO2)(d) Magnetite

(Q.6) What are the stoichiometric defects found in ionic crystals? ( 1 mark )

(Q.7) Write two examples of amorphous solids? ( 1 mark )

(Q.8) A solid substance XY has a rock salt geometry. What is the co-ordination number of X and Y? How many atoms of X and Y are present in the unit cell? ( 1 mark )

(Q.9) What type of solids are malleable, ductile and electrical conductors? ( 1 mark )

(Q.10) How many atoms are present in the unit cell of bcc and fcc? ( 1 mark )

(Q.11) Sometimes,common salt is yellow instead of being pure white. Why? ( 1 mark )

(Q.12) What are voids?
( 1 mark )

(Q.13) What happens when ferrimagnetic Fe3O4 is heated to 850 K?
( 1 mark )

(Q.14) Name thepoint defect which lowers the density of a crystal.
( 1 mark )

(Q.15) What is the co-ordination number of Na+ and Cl- ions in NaCl structure? ( 1 mark )

(Q.16) What do you mean by F-center?
( 1 mark )

(Q.17) Name the type of solids which have long range orders.
( 1 mark )

(Q.18) Name one solid which has both Frenkel and Schottky defects?
( 1 mark )

(Q.19) Why is the window glass of the old building thick at the bottom? ( 1 mark )

(Q.20) What causes the conduction of electricity by semiconductors? ( 1 mark )

(Q.21) Which salt can be added to AgCl so as to produce cationic vacancies? ( 1 mark )

(Q.22) Define photovoltaic cell? ( 1 mark )

(Q.23) Name a transition metal oxide which has appreance and conductivity like that of Cu? ( 1 mark )

(Q.24) What is the co-ordination number of an atom present inoctahedral void? ( 1 mark )

(Q.25) Write one property which is caused due to the presence of F-center in a solid. ( 1 mark )

(Q.26) The crystal system of a compound with unit cell dimensions a=0.387, b=0.387 and c=0.504nm and α=β=900 and =1200 is:
( 1 mark )
(a) Cubic(b) Hexagonal(c) Orthorhombic(d) Rhombohedral

(Q.27) Which of the following is non-stoichiometric defect: ( 1 mark )
(a) Frenkel defect(b) Metal excess defect(c) Thermodynamic defect(d) Intrinsic defect

(Q.28) What is the coordination number of Cl- in NaCl crystal? ( 1 mark )
(a) 8(b) 6(c) 4(d) 3

(Q.29) On adding little phosphorous to silicon, we get a/an ( 1 mark )
(a) n-Type semiconductor(b) p-Type semiconductor(c) Metallic conductor(d) Insulator

(Q.30) A semiconductor of Ge can be made p-type by adding: ( 1 mark )
(a) Trivalent impurity(b) Tetravalent impurity(c) Pentavalent impurity(d) Divalent impurity

(Q.31) The electrical conductivity of semiconductors ( 1 mark )
(a) Increases with temperature(b) Decreases with temperature(c) Remains constant
(d) Depends upon pressure

(Q.32) When molten zinc is cooled to solid state it assumes HCP structure. Then the number of nearest neighbours of zinc atom will be: ( 1 mark )
(a) 4(b) 6(c) 8(d) 12

(Q.33) Silicon can be converted into n-type semiconductor by adding impurityto it. Numberof valence electrons present in the impurity must be: ( 1 mark )
(a) 2(b) 5(c) 3(d) 1

(Q.34) In NaCl the chloride ions occupy the space in a fashion of: ( 1 mark )
(a) fcc(b) bcc(c) ccp(d) hcp

(Q.35) Which of the following has Frenkel defect? ( 1 mark )
(a) NaCl(b) Graphite(c) Silver bromide(d) Diamond

(Q.36) The number of octahedral sites per sphere in fccstructure is: ( 1 mark )
(a) 8(b) 4(c) 2(d) 1

(Q.37) The number of unit cells in 58.5gm NaCl is nearly: ( 1 mark )
(a) 6 X 1020(b) 3 X1022(c) 1.45 X 1023(d) 0.5 X 1024

(Q.38) Piezoelectric crystals are used in ( 1 mark )
(a) Radio(b) TV(c) Record player(d) Refrigerator

(Q.39) Solid CO2 is an example of ( 1 mark )
(a) Ionic solids(b) Covalent solids(c) Metallic solids(d) Molecular solids

(Q.40) How many kinds of space lattices are possible in a crystal? ( 1 mark )
(a) 7 (b) 14(c) 23(d) 200

(Q.41) In the crystal of which the following ionic compounds would you expect maximum distance between the centers of the cations and anions? ( 1 mark )
(a) LiF(b) CsF(c) CsI(d) LiI

(Q.42) In a solid lattice the cation left its usual lattice site and is located at an interstitial position, the lattice defect is ( 1 mark )
(a) Interstitial defects(b) Valency defect(c) Frenkel defect(d) Schottky defect

(Q.43) Atoms of element B form hcp lattice and those of the element A occupy 2/3rd of tetrahedral voids.What is the formula of the compound formed by the element A and B. ( 1 mark )
(a) A3B4(b) A4B3(c) A2B3(d) A3B2

(Q.44) A metallic crystal crystallizes into a lattice containing a sequence of layers AB AB AB ……Any packing of spheres leaves out voids in the lattice. What % by volume of this lattice is empty space? ( 1 mark )
(a) 74(b) 26(c) 50(d) None of these

(Q.45) Which substance will conduct electricity in the solid state? ( 1 mark )
(a) Diamond(b) Iodine(c) Graphite(d) NaCl (Solid)

(Q.46) When sodium chloride is doped with MgCl2 it produces ( 1 mark )
(a) Magnetic substance(b) cation vacancy(c) anion vacancy(d) none of these

(Q.47) If Indium is added in small quantity of Ge metal, we get ( 1 mark )
(a) An n-type semiconductor(b) An p-type semiconductor(c) Rectifier(d) Insulator

(Q.48) What is the coordination number of atominccp ? ( 1 mark )
(a) 4(b) 8(c) 12(d) 18

(Q.49) Which of the following is weakly repelled by magnetic field? ( 1 mark )
(a) Ferromagnetic substance(b) Paramagnetic substance(c) Diamagnetic substance
(d) Ferrimagnetic substance

(Q.50) Which of the followings possess zero resistance at room temperature or low temperature? ( 1 mark )
(a) Conductors(b) Semiconductors(c) Superconductors(d) Insulators

(Q.51) Certain crystals produce electric signals on application of pressure. This phenomenon is called: ( 1 mark )
(a) pyroelectricity(b) ferroelectricity(c) piezoelectricity(d) ferrielectricity

(Q.52) Which of the following is a molecular solid? ( 1 mark )
(a) Sodium chloride(b) Iron(c) Ice(d) Graphite

(Q.53) A compound formed by elements X and Y crystallizes in a cubic structure in which the X atoms are at the corners of a cube and the Y atoms are at the face centres. The formula of the compound is ( 1 mark )
(a) XY3(b) X3Y(c) XY(d) XY2

(Q.54) Germanium is an example of ( 1 mark )
(a) An intrinsic semiconductor(b) Ann-type semiconductor(c) Anp-type semiconductor
(d) Insulator

(Q.55) Which of the following crystals does not exhibit Frenkel defect? ( 1 mark )
(a) AgBr(b) AgCl(c) KBr(d) ZnS

(Q.56) The density of crystal changes when it has ( 1 mark )
(a) Schottky defect(b) Frenkel defect(c) Metal excess defect(d) Impurity defect

(Q.57) The addition of CaCl2crystal to KCl crystal ( 1 mark )
(a) lowers the density of the KCl crystal(b) raises the density of the KCl crystal
(c) does not affect the density of the KCl crystal
(d) increases the Frenkel defect of the KCl crystal

(Q.58) In the fluorite structure, the coordination number of Ca2+ion is ( 1 mark )
(a) 4(b) 6(c) 8(d) 3

(Q.59) How many particles are there in a fcc unit cell of a monoatomic substance? ( 1 mark )
(a) 1(b) 2(c) 4(d) 6

(Q.60) A solid with high electrical and thermal conductivity from the following is ( 1 mark )
(a) Si(b) Li(c) NaCl(d) Ice

(Q.61) p-type semiconductors are produced by ( 1 mark )
(a) doping germanium with phosphorus(b) doping germanium with aluminium
(c) doping silicon with arsenic(d) None of these

(Q.62) Packing efficiency is highest in ( 1 mark )
(a) hcp(b) bcc(c) simple cubic lattice(d) none of these

(Q.63) A compound formed by elements A and B crystallises in cubic structure where A atoms are at the corners of a cube and B atoms are at the face centre. What is the formula of the compound? ( 1 mark )
(a) AB(b) AB2(c) A2B(d) AB4

(Q.64) Which of the following is true statement? ( 1 mark )
(a) Crystalline solids are isotropic in nature(b) Amorphous solids have definite heat of fusion(c) The constituent particles of molecular solidare atoms(d) Amorphous solids are isotropic in nature

(Q.65) For a covalent solid, the units which occupy lattice points are ( 1 mark )
(a) Atoms(b) Ions(c) Molecules(d) Electrons

(Q.66) Pure silicon and germanium are: ( 1 mark )
(a) Conductors(b) Insulators(c) Semiconductors(d) None of these

(Q.67) Define body centred and face centred cubic system. ( 2 Marks )

(Q.68) Define: (i) Crystal lattice (ii) Co-ordination number ( 2 Marks )

(Q.69) What are- (i) Molecular solids (ii) Metallic solids ( 2 Marks )

(Q.70) What is rank? Find rank of face centered cubic unit cell. ( 2 Marks )

(Q.71) What is doping? How does n type and p type semiconductors differ from each other? ( 2 Marks )

(Q.72) Explain (i)Ferrimagnetism (ii)Semiconductors ( 2 Marks )

(Q.73) Write two differences between isotropy and anisotropy. ( 2 Marks )

(Q.74) Potassium metal crystallizes in bcc. The edge length of unit cell is 4.3 A0. Find the radius ofpotassium atom. ( 2 Marks )

(Q.75) Find the length of body diagonal of a cube having edge length of 250 pm. ( 2 Marks )

(Q.76) The edge length of unit cell of NaCl crystal lattice is 5.6A0. The density is 2.2g cm–3. Find the number of formula units of NaCl per unit cell. ( 2 Marks )

(Q.77) Find the number of NaCl molecules in a unit cell of its crystal. ( 2 Marks )

(Q.78) A compound is made of two atoms X and Y. Atom X is arranged in ccp and atom Y occupies tetrahedral site. Find the formula of compound. ( 2 Marks )

(Q.79) A metal crystallizes as face centered cubic lattice with edge length of 450pm. Molar mass of metal is 50g mol–1. Find the density of metal. ( 2 Marks )

(Q.80) A solid has bcc structure. Distance of closest approach between two atoms is 1.73A0. Find edge length of cell. ( 2 Marks )

(Q.81) Classify the following solids as metallic; molecular,amorphous, covalent or ionic.
(i) SO2 (ii) Diamond (iii) I2 (iv) MgO (iv) Ag (v) Quartz (vi) Ar ( 3 Marks )

(Q.82) What are voids? How a tetrahedral void differ from octahedral void? ( 3 Marks )

(Q.83) The density of an atom is 7.2g cm–3. It has bcc structure. The edge length is 288pm.
How many atoms of element does 208g of element has? ( 3 Marks )

(Q.84) Find the type of lattice for cube having edge length of 400 pm, atomic wt. = 60 and density = 6.25 g/cc. ( 3 Marks )

(Q.85) A mineral contains Ca, O and Ti. Oxygen atoms are present at face centres, calcium atoms are present at corners and titanium atoms at centre of cube. Find the oxidation number of titanium in the mineral. ( 3 Marks )

(Q.86) KF has NaCl structure. Its density is 2.48g cm–3. Find distance between K+ and F– ions in KF. ( 3 Marks )

(Q.87) A metal oxide crystallizes in a hexagonal close packed array of oxide ions with two out of every three octahedral holes occupied by metal. Find formula of metal oxide. ( 3 Marks )

(Q.88) A metallic element has cubic lattice. Edge length of lattice cell is 2A0. The density of metal is 2.4g cm–3. How many units cell are present in 200g of metal. ( 3 Marks )

(Q.89) The density of NaCl crystal is 2.155g cm–3 and distance between Na+ and Cl– is 280 pm. Find value of Avogadro’s number. ( 3 Marks )

(Q.90) In a face centered cubic lattice atoms of A occupy corner of cell and that of B occupy face centers. One of the A atoms is missing from one corner of a unit cell. Find the simplest formula of compound. ( 3 Marks )

(Q.91) Define (i) Schottky defect (ii) Frankel defect(iii) Point defects (iv) Interstitials (v) Vacancy

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