CHEMISTRY solid state

Which of the following is true about the charge acquired by P type semiconductor?

• positive

• negative

• neutral

• depends on concentration of p impurities

to get a n-type semiconductor from silicon it should be dopped with a substance with valence

• 2

• 1

• 3

• 5

the total number of tetrahedral voids in the face centred unit cell is

• 6

• 8

• 10

• 12

which of the following point defects are shown by AgBr(s) Crystal

• A-Schottky defect

• B- Frankel defect

• C-metal excess defect

• C-metal deficiency defect

• A&B

in which pair most efficient packing is present

• hcp and bcc

• hcp and ccp

• bcc and ccp

• bcc and simple cubic cell

the percentage of empty space in a body-centered cubic arrangement is

• 74

• 68

• 32

• 26

which of the following statement is not true about the hexagonal close packing

• the coordination number is 12

• it has 74% packing efficiency

• tetrahedral void of the second layer are covered by the share of the third layer

• in this arrangement spheres of the fourth layer are exactly aligned with those of the first layer

in which of the following structures coordination number for cation and anion in the packed structure will be same

• Cl negative ions form fcc lattice and Na positive ions occupy all octahedral voids of the unit cell

• Ca2 positive from fcc lattice and F negative ions occupy all the 8 tetrahedral voids of the unit cell

• O2 negative ions from fcc lattice and Na positive ions occupy all the 8 tetrahedral volds of the unit cell

• S2 negative ions from fcc lattice and Zn two positive ions go into alternate tetrahedral was of the unit cell

what is the coordination number in a square close packing structure in two dimensions

• 2

• 3

• 4

• 6

which kind of defects are introduced by doping

• dislocation defect

• Schottkey defect

• frenkel defect

• electronic defect