Cubic close packing in three dimensions is
1. Triangular voids
2. Pattern of spheres is repeated in every fourth layer
3. Coordination number =4
4. Pattern of sphere is repeated in alternate layers
Number of octahedral voids are present per unit cell in a cubic close packed structure :
1. 4
2. 8
3. 6
4. 2
Number of tetrahedral voids voids are present per unit cell in a cubic close packed structure :
1. 4
2. 8
3. 6
4. 2
Doping affects the property of semiconductors. It -
1. Increases the conductivity of semiconductors.
2. Decreases the conductivity of semiconductors.
3. No effect on conductivity of semiconductors.
4. None of the above.
Non-stoichiometric defect present in the sample of ferrous oxide with formula Fe0.93O1.00 -
1. Metal deficiency defect
2. Metal excess defect
3. Frenkel defect
4. Schottky defect
Select the correct option based on statements below:
Assertion (A): | The stability of a crystal is reflected by the magnitude of its melting point. |
Reason (R): | Greater the intermolecular forces of attraction, the higher will be the stability and melting point of the substance. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
The packing efficiency of the face-centered cubic unit cell is:
(assuming that the atoms are touching each other)
1. 52.40 %
2. 68.04 %
3. 74 %
4. 79.06 %
Silver crystallizes in fcc lattice. If the edge length of the cell is 4.07 × 10−8 cm and density is 10.5 g cm−3, the atomic mass of silver is -
1. 120.31 g
2. 107.9 g
3. 207.60 g
4. 138.52 g
Copper crystallizes into an fcc lattice with an edge length of 3.61 × 10−8 cm. The density of copper crystal will be -
1. 7.46 g cm-3
2. 9.67 g cm-3
3. 8.96 g cm-3
4. 5.63 g cm-3
Nickel oxide has the formula Ni0.98O1.00. The fraction of nickel existing as Ni3+ ions will be -
1. 0.041
2. 0.959
3. 0.736
4. 0.264