Which of the following is considered a flammable liquid?

Acetone is recognized as a flammable liquid due to its low flash point and high volatility. Flammable liquids are defined by their ability to ignite easily and create harmful fire and explosion hazards. Acetone has a flash point of approximately 20°C (68°F), meaning it can produce enough vapor to form an ignitable mixture with air at relatively low temperatures, making it pose significant risks in various environments, especially if not stored or handled properly.

In contrast, water, sand, and calcium carbonate do not possess flammable properties. Water is an effective fire suppressant and non-combustible. Sand acts as a non-flammable material often used as an insulating barrier or to smother fires. Calcium carbonate, primarily found in limestone, is non-flammable and does not combust under standard conditions. Thus, acetone stands out as the only flammable liquid among the options provided.