The formula of nickel oxide with metal deficiency defect in its crystal is . The crystal contains ions. The fraction of nickel existing as ions in the crystal is-
1. 0.96
2. 0.04
3. 0.50
4. 0.31
A compound is formed by cation C and anion A. The anions form hexagonal close packed (hcp) lattice and the cations occupy 75 % of octahedral voids. The formula of the compound is:
1.
2.
3.
4.
An element has a body-centered cubic (BCC) structure with a cell edge of 288 pm. The atomic radius is:
1. pm
2. pm
3. pm
4. pm
A compounds that can show both, Frenkel as well as Schottky defects is -
1. AgBr
2. AgI
3. NaCl
4. ZnS
The number of tetrahedral and octahedral voids in hexagonal primitive unit cell are respectively:
1. 2, 1
2. 12, 6
3. 8, 4
4. 6, 12
The correct option for the number of body centred unit cells in all 14 types of Bravais lattice unit cells is :
1. 2
2. 3
3. 7
4. 5
Assertion (A): | In a particular point defect, an ionic solid is electrically neutral, even if few of its cations are missing from its unit cells. |
Reason (R): | In an ionic solid, Frenkel defect arises due to dislocation of cation from its lattice site to interstitial site, maintaining overall electrical neutrality. |
1. | (A) is false but (R) is true. |
2. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
3. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
4. | (A) is true but (R) is false. |
A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:
1. | all the domains get oriented in the direction opposite to the direction of magnetic field. |
2. | domains are not affected by magnetic field. |
3. | domains get randomly oriented. |
4. | all the domains get oriented in the direction of magnetic field. |
Which statements among the following is not correct?
1. | When conduction band and valence band overlap, a semiconductor is obtained |
2. | Ferrimagnetism arises due to the alignment of magnetic moments of the domains in the substance in parallel and anti-parallel directions in unequal numbers |
3. | Replacing some silicon atoms by boron atoms in crystal of silicon produces p-type semiconductor |
4. | Replacing some germanium atoms by phosphorus atoms in a crystal of germanium produces n-type semiconductor |