Che01

Which one of the following is non-crystalline or amorphous ?

• (A) Diamond

• (B) Graphite

• (C) Glass

• (D) Common Salt

In fcc cubic cell, an atom at the face centre is shared by

• (A) 6 unit cell

• (B) 1 unit cell

• (C) 2 unit cells

• (D) 4 unit cell

Silicon doped with electron rich impurity forms

• (A) p-type semiconductor

• (B) n-type semiconductor

• (C) intrinsic semiconductor

• (D) insulator

The correct order of the packing efficiency in different types of unit cells is

• (A) fcc < bcc < simple cubic

• (B) fcc < bcc < simple cubic

• (C) fcc < bcc < simple cubic

• (D) bcc < fcc < simple cubic

What is the coordination number in a square close packed structure in two dimensions ?

• 2

• 3

• 4

• 6

The percentage of empty space in a body centred cubic arrangement is

• 74

• 68

• 32

• 23

What is the co-ordination number of sodium in Na₂ O ?

• 6

• 4

• 8

• 2

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

• 6

• 8

• 10

• 12

To get a n-type semiconductor from silicon, it should be doped with a substance with valence

• 2

• 3

• 5

• 1

Graphite cannot be classified as

• (A) conducting solid

• (B) network solid

• (C) covalent solid

• (D) ionic solidg