Which of the following elements are semiconductors? C, Si, Ge, Sn C and Si only

Question

Which of the following elements are semiconductors? C, Si, Ge, Sn C and Si only Si and greaterthanorequalto only greaterthanorequalto and Sn only None of these elements are semiconductors unless a dopant is added. All of these elements are semiconductors. The two types of closest-packed lattices are cubic closest-packed and face-centered cubic. cubic closest-packed and hexagonal closest-packed. cubic closest-packed and random closest-packed. cubic closest-packed and pyramidal closest-packed. simple cubic and hexagonal closest-packed. In the sodium chloride unit cell, the chloride ions form a cube in which each side is arranged like the following figure. The circles represent the positions of the chloride ions on one square face of the cube. All the other faces are the same. What is the name of this unit cell? Cubic chloride-centered cubic face-centered cubic x-face cubic body-centered cubic Polonium crystallizes in a simple cubic pattern. How many polonium atoms are in each unit cell? 1 2 3 4 5 Iron crystallizes in a body-centered cubic pattern. How many iron atoms are in each unit cell? 1 2 4 8 9 Copper crystallizes in a face-centered cubic pattern. How many copper atoms are in each unit cell? 2 4 8 12 14

Explanation / Answer

15.

C is a non metal, Sn is a metal, Si and Ge are semiconductors.

So option b is correct.

16.

The two types of closest packed lattices are cubic closed and hexagonal closed. They diifer in how we place the third layer of atoms after second layer.

So option b is correct.

17.

there are atoms on the corner of the cube and one atom in the centre. So its a body centred vubic lattice.

option e is correct.

18.

In simple cubic, we have 8 atoms at the 8 corners of the unit cell. but the coordination number of cubic cell is 8. i.e each atom at the corner is shared by 8 adjacent atoms. So 1/8 th part is with one unit cell. total= 8*(1/8)= 1.

so option 1 is correct.

19.

for corners, follow question 18. now in body centred lattice, in addition to atoms on the corner we have one in the centre also which is nit shared by any other unit cell. it wholly belongs to that particular unit cell.

so total number of atoms=1+1 =2 . optionb is correct.

20.

In face centred, in addition to corner atoms, each face of cube has one atom in the centre, which is hared by two unit cells.

total faces= 6

share of one unit cell per atom=1/2

so no. of atoms in one unit cell for faces= 6*(1/2)= 3

total=1+3=4

option b is correct.

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