What are the physical characteristics of carbon dioxide (CO₂)?

The correct answer describes the physical characteristics of carbon dioxide (CO₂) as colorless, odorless, and having a slightly acidic taste. CO₂ is a gas at room temperature and pressure, and it does not exhibit color or odor, making it undetectable through sight or smell. The slightly acidic taste is a unique property of carbon dioxide when it dissolves in water, forming carbonic acid, which gives it a mild acidic flavor. This characteristic is often noticeable in carbonated beverages, where the presence of dissolved CO₂ contributes to the drink's taste profile.

In contrast, the other options misrepresent one or more characteristics of CO₂. For example, the presence of an odor or a specific taste description like "sweet-tasting" in the second option does not align with the established properties of carbon dioxide. Additionally, the description of color and taste in the fourth option is inaccurate, as carbon dioxide is not blue, nor is it associated with a bitter taste. This is important for understanding the safe handling and application of CO₂ in medical and industrial settings, where its properties influence usage and safety protocols.