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 pair having only molecular solids among the following is -
1. Brass and SiC
2. Ammonium phosphate (NH4)3PO4
3. SiC and plastic
4. Tetra phosphorus decaoxide (P4O10) and I2
The number of lattice points in one unit cell of face-centred tetragonal lattice is -
1. 4
2. 12
3. 14
4. 9
The similarity between metallic and ionic crystals is -
1. | Both these crystal types are held by the electrostatic force of attraction. |
2. | Both these crystal types are held by the Van der Waal's forces of attraction. |
3. | Both these crystal types are held by hydrogen bonding. |
4. | Both these crystal types are held by covalent bonding. |
Aluminum crystallizes in a cubic close-packed structure. It's metallic radius is 125 pm. The number of unit cells in 1.00 cm3 of aluminum are :
1. 2.27 x 1022
2. 354 x 1022
3. 4.54 x 1022
4. 127 x 1020