Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

The Solid State

Short Answer Type

121. Give reasons for Non-stoichiometric sodium chloride is a yellow solid.

441 Views

Long Answer Type

122. What is a semi-conductor? Describe the two main types of semi-conductors and contrast their conduction mechanism.

231 Views

123. A cubic solid is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body centre. What is the formula of the compound? What are the coordination numbers of P and Q?

Formula of a compound is same as the formula of unit cell. An atom at the corner of cube contributes only l/8th to the unit cell and there are 8 corners in a cube.
∴ No. of atoms of Q in the unit cell

= 8 \times \frac{1}{8} = 1 .

An atom at centre of cube belongs only to this unit cell and there is only one body centre in the unit cell.
∴ No. of atoms of P in the unit cell = 1 x 1 = 1
Thus, the formula of compound is PQ or QP.
For body centred cubic unit cell, the coordination number is 8:8.
∴ Co-ordination number P = 8 and also coordination number of Q = 8.

272 Views

Short Answer Type

124. What is the difference between Schottky defects and Frenkel defects?

1326 Views

Long Answer Type

125. If the radius of the octahedral void is r and radius of the atoms in close packing is R, derive relation between r and R.

460 Views

Short Answer Type

126. Pure silicon is an insulator. Silicon doped with phosphorus is a semi-conductor. Silicon doped with gallium is also a semiconductor. What is the difference between the two doped silicon semi-conductor?

1060 Views

Long Answer Type

127. What are paramagnetic and ferromagnetic substances. Account for the paramagnetic character of transition metal compounds. How does the paramagnetic character of the bivalent ions of the first transition metal series varies from Ti (Z = 22) to Cu (Z = 29)?

344 Views

128. Non-stoichiometric cuprous oxide, Cu₂O can be prepared in laboratory. In this oxide, copper to oxygen ratio is slightly less than 2 :1. Can you account for the fact that this substance is a p-type semi-conductor ?

827 Views

Short Answer Type

129. Ferric oxide crystallizes in a hexagonal close packed array of oxide ions with two out of every three tetrahedral holes occupied by ferric ions. Derive the formula of the ferric oxide.

177 Views

Long Answer Type

130. Classify each of the following as being either a p-type or an n-type semi conducor:
(i) Ge doped with In
(ii) B doped with Si.

198 Views