Which statement about fuel/air ratios is true?

The statement regarding fuel/air ratios that is true is that the mixture ratio for best power is richer than that for maximum economy. In reciprocating engines, fuel/air mixture ratios play a crucial role in performance characteristics. When the mixture is richer, meaning it has a higher fuel content relative to air, it increases the amount of fuel available for combustion, leading to more power being generated. This is essential during conditions such as take-off or high-load situations where maximum power is required.

In contrast, for maximum economy, which is often desired during cruise conditions, a leaner mixture (less fuel relative to air) is usually more efficient. This leaner mixture conserves fuel by providing just enough fuel for efficient combustion without excessive waste. Therefore, while a richer mixture facilitates greater power output, it is not as efficient in terms of fuel consumption, which explains why the two conditions have different optimal mixture settings.

Overall, understanding the relationship between fuel/air ratios allows for proper engine management to optimize either power or efficiency depending on the operating conditions.