 A number of facts about crystalline solids are stated below. Choose the number of the response that best explains the applicability of this representation, or model, for each fact. [Note: Choose only one response for each fact.]
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A crystalline solid may be represented as a 3-dimensional array of spheres with each sphere connected to its neighbors by a stiff spring. The spheres are vibrating in various directions.
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RESPONSES
- The fact is explained by the representation or model shown.
- The fact can be explained by modifying the model as follows: the amplitude of vibration of the spheres depends upon the temperature.
- The fact can be explained by modifying the model as follows: there are irregularities in the arrangement of spheres.
- The fact can be explained by modifying the model as follows: the elasticity of the springs is different for different solids.
- The fact cannot be explained on the basis of the representation or model, even by changing it as above.
FACTS
- Solids contract on cooling.
- Solids may be compressed slightly.
- Solids do not diffuse through one another.
- Solids conduct heat.
- Some solids are harder than others.
- The speed of sound through steel is greater than its speed through lead.
Source: Adapted from Handbook on Formative and Summative Evaluation of Student Learning by B. S. Bloom, J. T. Hastings, & G. F. Madaus, McGraw Hill, 1971, p612.
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