On doping Ge metal with a little of In or Ga, one gets

Solution

p-type of semiconductors are produced
(i)due to metal deficiency defects
(ii)by adding impurity containing less electrons (i.e.,atoms of group 13)Ge belongs to Group 14 and In to Group 13. Hence on doping, p-type semicondutor is obtained.

Schottky defect defines imperfection in the lattice structure of

Doping of silicon (Si) with boron (B) leads to:

Each of the following solids show, the Frenkel defect except

Solution

In KCl, co-ordination number of cation and anion is 6 and 6 respectively. KCl is highly ionic so Schottky defect is common.
Note :Schottky defect is common in compounds having high coordination nummber while Frenkel defect is common in compounds with low coordination number.

Coordination numbers of Zn2+ and S2– in the crystal structure of wurtzite are

Solution

Wurtzite has face centred cubic structure in which each Zn²⁺ ion is attached to four S^2- ions and each S^2- ion remains in contact with four Zn²⁺ ions. Hence coordination number of each ion is 4.

The cubic unit cell of a metal (molar mass = 63.55g mol^-1) has an edge length of 362 pm. Its density is 8.92 g cm^-3.The type of unit cell is

The radii of Na⁺ and Cl^– ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is

Pottasium has a bcc structure with nearest neighbour distance 4.52 Å. Its atomic weight is 39.Its density (in kg m^-3)will be

The number of atoms in 100 g of an fcc crystal with density,d= 10g/cm³ and cell edge equal to 100 pm, is equal to

An element occuring in the bcc structure has 12.08 × 1023 unit cells.The total number of atoms of the element in these cells will be

Solution

There are two atoms in a bcc unit cell.So, number of atoms in 12.08 × 10²³ unit cells= 2 × 12.08 × 10²³ = 24.16× 10²³ atoms

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