1. Which of the following is NOT a characteristic of crystalline solids?
Answer:
Explanation:
Crystalline solids are anisotropic in nature, meaning they have different properties in different directions.
2. In which type of solid are the constituent particles positive ions surrounded by a sea of delocalized electrons?
Answer:
Explanation:
Metallic solids consist of positive ions in a sea of delocalized electrons, giving them unique properties.
3. Which type of defect does not alter the density of a crystal?
Answer:
Explanation:
In a Frenkel defect, an ion leaves its place and occupies an interstitial site. This does not cause a change in the density of the crystal.
4. In a face-centered cubic (FCC) lattice, an atom at the corner contributes how much to the unit cell?
Answer:
Explanation:
In FCC, an atom at the corner is shared by eight adjacent unit cells, so it contributes 1/8 to each.
5. Which type of solid is dry ice?
Answer:
Explanation:
Dry ice is solid carbon dioxide, a molecular solid with molecules as its constituent particles.
6. Which of the following is a characteristic of amorphous solids?
Answer:
Explanation:
Amorphous solids have a short-range order but lack a long-range order, making them different from crystalline solids.
7. What type of crystal defect is introduced by doping in semiconductors?
Answer:
Explanation:
Doping in semiconductors introduces an impurity defect where foreign atoms replace the host atoms.
8. Which solid has the highest melting point?
Answer:
Explanation:
Covalent solids, like diamond, have extremely strong covalent bonds, giving them very high melting points.
9. In which type of solid are constituent particles held together by van der Waals forces?
Answer:
Explanation:
Molecular solids are held together by van der Waals forces or hydrogen bonding.
10. What is the coordination number of an atom in a body-centered cubic (BCC) lattice?
Answer:
Explanation:
In a BCC lattice, each atom is surrounded by 8 neighboring atoms.
11. Which defect is observed when some of the lattice sites are vacant?
Answer:
Explanation:
Schottky defect arises when equal numbers of cations and anions are missing from the lattice.
12. In which of the following solids is electrical conductivity high and increases with increasing temperature?
Answer:
Explanation:
Semiconductors have moderate electrical conductivity, which increases with temperature.
13. Which of the following is a property of n-type semiconductors?
Answer:
Explanation:
n-type semiconductors are obtained by doping pentavalent impurities, and electrons become the majority carriers.
14. How many atoms are present in one unit cell of a face-centered cubic crystal?
Answer:
Explanation:
In FCC, there are 8 corner atoms (1/8 each) and 6 face-centered atoms (1/2 each), totaling 4 atoms.
15. Which of the following is NOT a point defect?
Answer:
Explanation:
Grain boundary is an example of a line defect, not a point defect.
16. Which type of crystal shows electrical neutrality?
Answer:
Explanation:
Both Schottky and Frenkel defects maintain electrical neutrality in the crystal.
17. What type of solid is graphite?
Answer:
Explanation:
Graphite is made of layers of carbon atoms bonded in a hexagonal lattice, making it a covalent solid.
18. What is the coordination number of an atom in a simple cubic lattice?
Answer:
Explanation:
In a simple cubic lattice, each atom is surrounded by 6 neighboring atoms.
19. Which of the following is a ferromagnetic material?
Answer:
Explanation:
Iron is a ferromagnetic material, meaning it can be magnetized or attracted to a magnet.
20. Which type of crystal lattice does Sodium Chloride (NaCl) adopt?
Answer:
Explanation:
Sodium Chloride (NaCl) adopts the face-centered cubic (FCC) lattice structure.