Final answer:
A plate of pasta with sauce and meatballs is a heterogeneous mixture with visible, separate components, while air is a homogeneous mixture with gases mixed so evenly they can't be distinguished by sight.
Step-by-step explanation:
A mixture can come in many forms, exemplified by a plate of pasta with sauce and meatballs versus the mixture of air. The pasta dish is a heterogeneous mixture because its components – pasta, sauce, and meatballs – can be seen individually and are not mixed in a uniform way. Each bite might have a different ratio of pasta, sauce, and meatballs, just like how in a heterogeneous mixture, such as Italian dressing, the composition can vary throughout the mixture. Conversely, air is a homogeneous mixture, meaning it is uniform in composition. The different gases in air (like oxygen, nitrogen, and carbon dioxide) are mixed so evenly that you can't distinguish them by sight, even under a microscope. Moreover, the components in the air are not in a fixed ratio and retain their properties just as the individual ingredients in the pasta retain theirs.