The unit cell dimensions of a cubic lattice (edges a, b, c and the angles between them, α, β, γ) are :
1. a = b = c,
2. a = b c,
3. a = b = c,
4. a b c,
Assertion (A): | The total number of atoms present in a simple cubic unit cell is one. |
Reason (R): | Simple cubic unit cell has atoms at its corners, each of which is shared between eight adjacent unit cells. |
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. | (A) is false but (R) is true. |
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. |
Lithium metal crystallizes in a body-centered cubic crystal. If the length of the side of the unit cell of lithium is 351 pm, the atomic radius of the lithium will be:
1. 240.8 pm
2. 151.8 pm
3. 75.5 pm
4. 300.5 pm
The incorrect statement among the following regarding crystalline solid is -
1. | Definite and characteristic heat of fusion. |
2. | Isotropic nature. |
3. | A regular periodically repeated pattern of arrangement of constituent particles in the entire crystal. |
4. | A true solid. |
Network solid, among the following, is :
1. SO2(solid)
2. I2
3. Diamond
4. H2O(ice)
The coordination number of a square close-packed structure in two dimensions is -
1. 2
2. 3
3. 4
4. 6
a. | The coordination number of a cation occupying a tetrahedral hole is 4. |
b. | The coordination number of a cation occupying an octahedral hole is 6. |
c. | In Schottky defect, the density of the lattice decreases. |
1. a, b
2. b, c
3. a, b, c
4. a, c
Incorrect statement among the following about amorphous solids is -
1. | On heating they may become crystalline at a certain temperature. |
2. | They may become crystalline on keeping for a long time. |
3. | Amorphous solids can be moulded by heating. |
4. | They are anisotropic in nature. |
An example of amorphous solid among the following is -
1. Graphite (C)
2. Quartz glass (SiO2)
3. Chrome alum
4. Silicon carbide (SiC)