Consider a lattice whose plane passing through two opposite

An element density 6 8 g cm3 occurs in bcc structure with cell edge of 290 pm Calculate the number of atoms present in 200 g of the element A B 24 12 x 1023 5 05 1021

WBSU Year 2011 1 a What do you mean by Compton effect A beam of X rays is scattered by loosely bound electrons of a target through 45 to the direction of the beam What is the amount of Compton shift rest mass of the electron 9 109 10 31 kg h 6 625x10 34 J s 4

Q16 The arrangement ABC ABC is referred to as 1 octahedral close packing 2 hexagonal clase packing 3 tetrahedral close packing 4 cubic close packing 1 2 55 3 From NCERT 4

5 A crystalline solid is made up of A B and C elements Atoms of A form fcc packing atoms of B occupy octahedral voids while atoms of C occupy tetrahedral voids Select the simplest formula if atoms are missing from one of the body diagonal 1 ABC 3 A5B4C8 2 AgB4C5 4 A BC 42 I t th e th fo 1 3

a Describe Frenkel defect by drawing suitable schematic diagram b Calculate the number of vacancies created when a given sample of sodium chloride is doped with 2 X 10 5 mol of aluminium chloride c Sample of KCI appears violet when it is heated in atmosphere of potassium vapours why d Zinc oxide crystal appears yellow on heating explain e What is the effect on density if a crystal is found to possess Schottky defect

2 In a hypothetical cubic lattice A atoms occupy the corners B atoms the face centers C atoms the body center and D atoms are present at the edge center sites If all the atoms lying on one of the diagonal planes are removed the empirical formula of the unit cell will be 1 A B4D5 3 AB4CD4 2 AB4D5 4 A B3D4

A solid is made up of three elements P Q and R Atoms P are in ccp arrangement Q atoms occupy 12 5 of the tetrahedral sites and R atoms occupy 50 octahedral voids What is the formula of the compound 1 Q RP 3 PQR 2 QR P4 4 P Q R

3 4 6 If radius of Zn 2 is a and that of S 2 is b then body diagonal of CCP lattice ZnS will be 1 4 a b 3 3 a b 2 2 a b 4 3 a b 2

4 6 9 A crystal is made of particle x y and z x forms f c c packing y occupies all the octahedral voides of x and z occupies all the tetrahedral voides of x If all particle along one body diagonal are removed the formula of the crystal would be 1 xyz2 2 X2YZ2 3 X Y ZE 4 M

30 In a face centered cubic arrangement of A and B atoms A atom are at the corner of the unit cell and B atoms at the face centres One of the B atoms is missing from one of the face in unit cell The simplest formula of compound is 1 AB3 3 A B5 31 The fraction of the total volum 2 AgB5 4 AB 2 5