A low-pressure, vacuum insulated vessel containing gas in liquid form is called?

The correct answer, which defines a low-pressure, vacuum insulated vessel that contains gas in liquid form, is "container." This term is broadly used in the context of gas handling and refers specifically to vessels designed to hold gases in liquid form under low pressure.

These containers are essential in various industrial and medical applications, including those involving cryogenic gases such as liquid oxygen or nitrous oxide. The vacuum insulation is critical because it helps maintain the low temperatures required to keep gases in their liquid state, ensuring they remain stable and effective for their intended use.

While an "appliance" typically refers to a device utilizing gas rather than storing it, a "cylinder" often indicates a high-pressure vessel used for storing gases, not necessarily in liquid form under low pressure. A "safety can" primarily refers to a container for flammable liquids with features designed to minimize the risk of ignition. Thus, "container" is the most accurate term for describing the vessel in question.