Why might different samples of brass melt at different temperatures?

• A. Because brass is a pure substance and always melts at the same temperature.
• B. Because the melting point of brass depends only on atmospheric pressure.
• C. Because brass samples are always contaminated with iron.
• D. Because the composition of brass can vary, leading to different melting points.

Answer: (D)

Verified step by step guidance

1. Understand that brass is an alloy, which means it is a mixture of two or more metals, primarily copper and zinc.
2. Recognize that the melting point of an alloy depends on its composition; different ratios of copper to zinc will change the melting temperature.
3. Recall that pure substances have a fixed melting point, but alloys like brass do not have a single, sharp melting point; instead, they melt over a range of temperatures.
4. Consider that impurities or variations in the amounts of other elements in brass can also affect its melting behavior.
5. Conclude that because the composition of brass can vary from sample to sample, the melting point is not constant and can differ accordingly.