30 short questions and answers on the topic "Solid State" for Class 12th Chemistry students:

 

Solid State - Short Questions and Answers

 

1.Question: What are crystalline solids?

Answer: Solids with a definite geometric shape and long-range order.

 

2.Question: What are amorphous solids?

Answer: Solids lacking a definite shape and having only short-range order.

 

3.Question: Give an example of a crystalline solid.

Answer: Sodium chloride (NaCl).

 

4.Question: Give an example of an amorphous solid.

Answer: Glass.

 

5.Question: What is a unit cell?

Answer: The smallest repeating structural unit of a crystalline solid.

 

6.Question: How many atoms are in a simple cubic unit cell?

Answer: One.

 

7.Question: How many atoms are in a body-cantered cubic unit cell?

Answer: Two.

 

8.Question: How many atoms are in a face-cantered cubic unit cell?

Answer: Four.

 

9.Question: What is packing efficiency?

Answer: The percentage of total space filled by constituent particles.

 

10.Question: What is the coordination number in a simple cubic lattice?

Answer: Six.

 

11.Question: What is the coordination number in a bcc lattice?

Answer: Eight.

 

12.Question: What is the coordination number in an fcc lattice?

Answer: Twelve.

 

13.Question: What are point defects?

Answer: Imperfections localized at or around a lattice point.

 

14.Question: What is a Schottky defect?

Answer: A vacancy defect where equal numbers of cations and anions are missing.

 

15.Question: What is a Frenkel defect?

Answer: A defect where an ion leaves its lattice site and occupies an interstitial site.

 

16.Question: Why do ionic solids conduct electricity in the molten state?

Answer: Due to the mobility of ions.

 

17.Question: What are metallic solids held together by?

Answer: Metallic bonds.

 

18.Question: What are covalent network solids?

Answer: Solids with atoms linked by a continuous network of covalent bonds.

 

19.Question: What holds molecular solids together?

Answer: Weak van der Waals forces.

 

20.Question: What is polymorphism?

Answer: The existence of a solid in more than one crystalline form.

 

21.Question: What is anisotropy?

Answer: The property of showing different physical properties in different directions.

 

22.Question: What is isotropy?

Answer: The property of showing the same physical properties in all directions.

 

23.Question: What causes the conductivity of metallic solids?

Answer: Mobile electrons.

 

24.Question: What is the relationship between edge length (a) and radius (r) in a simple cubic cell?

Answer: a = 2r.

 

25.Question: What is the relationship between edge length (a) and radius (r) in an fcc cell?

Answer: a = 2√2 r.

 

26.Question: What is the relationship between edge length (a) and radius (r) in a bcc cell?

Answer: a = 4r/√3.

 

27.Question: Which defect decreases the density of a solid?

Answer: Schottky defect.

 

28.Question: What are F-centres?

Answer: Anion vacancies occupied by unpaired electrons, causing colour.

 

29.Question: What are n-type semiconductors doped with?

Answer: Electron-rich impurities.

 

30.Question: What are p-type semiconductors doped with?

Answer: Electron-deficient impurities.