21786.Match Column A with B and select the correct option.
| Column A | Column B | ||
|---|---|---|---|
| A | Ionic solid | I | NaCl |
| B | Metallic solid | II | Fe |
| C | Covalent solid | III | C (graphite) |
| D | Molecular solid | IV | Dry ice |
A – II, B – I, C – IV, D – III
A – I, B – II, C – III, D – IV
A – III, B – II, C – I, D – IV
A – II, B – IV, C – I, D – III
21787.The cubic unit cell of a metal (molar mass = 63.55 g mol–1) has an edge length of 362 pm. Its density is 8.92 g cm3. The type of unit cell is:
Body centred
Face centred
Primitive
End centred
21788.Density of a crystal remains unchanged as a result of
Vacancy defect
Interstitial defect
Frankel defect
Schottky defect
21791.Which of the following statements about amorphous solids is incorrect?
They melt over a range of temperature.
They are rigid and incompressible.
There is no orderly arrangement of particles.
They are anisotropic.
21793.The ionic radii of A+ and B– ions are 0.98 ×10–10 m and 1.81 × 10–10 m. The coordination number of each ion in AB is
8
2
6
4
21794.Which among the following solids crystalises as a face centred cube?
Iron
Rubidium
Uranium
Platinum
21795.A crystalline solid XY3 has ccp arrangement for its element Y. X occupies
66% of tetrahedral voids
33% of tetrahedral voids
66% of octahedral voids
33% of octahedral voids