Which statement about the coefficient of expansion of metals is true?

The statement that the coefficient of expansion is greater for aluminum than for steel is accurate and reflects important properties of these metals. The coefficient of thermal expansion indicates how much a material expands when its temperature increases. Different metals have different coefficients due to their atomic structures and bonding.

Aluminum typically has a higher coefficient of thermal expansion compared to steel, which means that for the same temperature increase, aluminum will expand more than steel. This property is critical in engineering applications, especially where metals are used together or in environments subject to temperature variations, as it can influence design decisions to prevent structural failures, such as warping or joint separation.

In contrast, suggesting that the coefficient of expansion is a constant for all non-ferrous metals is misleading since each non-ferrous metal, like copper or brass, will have its unique coefficient based on its physical properties. The units of measurement for the coefficient of thermal expansion are typically given in terms of length per length, such as "per degree Celsius" rather than in centimeters per meter. Also, the idea that all metals share the same coefficient is incorrect; each metal possesses distinct thermal expansion characteristics that must be understood for effective application in engineering designs.