Which of the following materials has a greater rate of expansion than copper?

• A. Aluminum
• B. Magnesium
• C. Tin
• D. Bronze

Answer: (D)

The correct answer is the material that demonstrates a greater rate of thermal expansion than copper. When comparing thermal expansion properties, aluminum and magnesium are known to have higher coefficients of thermal expansion than copper, while bronze typically has a lower rate.

Copper has a coefficient of thermal expansion around 16 x 10^-6 per °C. On the other hand, aluminum generally has a coefficient of approximately 23 x 10^-6 per °C, which indicates it expands more than copper when subjected to temperature changes. Magnesium also has a coefficient of expansion greater than that of copper, further supporting its ability to expand at a higher rate.

Tin, meanwhile, has a coefficient that is somewhat comparable to copper but is still lower than aluminum and magnesium. Bronze, as an alloy primarily composed of copper, typically has a thermal expansion rate that is similar or slightly lower than that of copper due to the characteristics imparted by its alloying elements.

In summary, both aluminum and magnesium expand more than copper, making either of them the correct answer over bronze and tin in terms of thermal expansion properties.