Chapter Test 2: The Solid State

 Chapter Test:

The Solid State

Time Limit: 1 hour

Multiple Choice Questions:

1. Which of the following is an example of a crystalline solid? a) Glass b) Plastic c) Rubber d) Sodium chloride

2. The crystal system that has three unequal axes intersecting at oblique angles is: a) Cubic b) Monoclinic c) Orthorhombic d) Hexagonal

3. The coordination number of an atom in a body-centered cubic (bcc) lattice is: a) 4 b) 6 c) 8 d) 12

4. Which of the following defects is caused by the presence of an extra atom in the lattice site? a) Frenkel defect b) Schottky defect c) Vacancy defect d) Interstitial defect

5. The process of adding impurities to a semiconductor to modify its electrical conductivity is called: a) Doping b) Annealing c) Sintering d) Alloying

Short-Answer Questions:

1. Define the term "crystalline solids" and provide two examples.

2. Explain the concept of a unit cell and its significance in the study of solids.

3. Describe the concept of "close packing" in solids and discuss the difference between hexagonal close packing (hcp) and cubic close packing (ccp).

4. Discuss the types of point defects in solids and provide examples for each.

5. Explain the concept of "polymorphism" and provide an example of a polymorphic solid.

Solutions:

Multiple Choice Questions:

1. d) Sodium chloride
2. b) Monoclinic
3. c) 8
4. d) Interstitial defect
5. a) Doping

Short-Answer Questions:

1. Crystalline solids are solids that have a well-defined arrangement of particles in a regular repeating pattern called a crystal lattice. Examples: Sodium chloride (NaCl), Diamond (C).

2. A unit cell is the smallest repeating unit of a crystal lattice that represents the entire crystal structure. It helps in understanding the overall arrangement and symmetry of the crystal lattice.

3. Close packing refers to the arrangement of particles in a solid to maximize the efficiency of space. In hexagonal close packing (hcp), the particles are arranged in a close-packed hexagonal pattern, while in cubic close packing (ccp), the particles are arranged in a close-packed cubic pattern.

4. Point defects in solids refer to deviations from the regular arrangement of particles in the crystal lattice. Examples: Vacancy defect, where an atom or ion is missing from its lattice site, and interstitial defect, where an atom or ion occupies an interstitial site between the lattice points.

5. Polymorphism is the property of certain solids to exist in more than one crystal structure. An example is carbon, which can exist in multiple forms such as graphite and diamond.