What is the correct chemical formula for dry ice?

The correct chemical formula for dry ice is CO2. Dry ice is the solid form of carbon dioxide, which is a colorless gas at room temperature. When carbon dioxide is subjected to high pressure and then allowed to rapidly expand, it solidifies, forming dry ice. This substance is widely used for cooling and preserving food, creating fog effects, and in various industrial applications due to its ability to maintain low temperatures.

The other options represent different compounds: H2O is the formula for water, essential for all known life forms; NaCl is table salt, composed of sodium and chlorine, commonly used as a seasoning and preservative; and C6H12O6 is glucose, a simple sugar that serves as an important energy source in biological organisms. Understanding these compounds highlights the uniqueness of CO2 as the specific combination of carbon and oxygen that makes dry ice distinct, both in its composition and its physical properties.