Temperature is measured using a tool called a thermometer. In its simplest form, a thermometer is a glass tube filled with a liquid called a thermometric medium. As the thermometer is exposed to heat, the thermometric medium’s molecules begin to move around and spread out, causing it to expand into the tube. How much it expands depends on how much the temperature has changed. One common thermometric medium is mercury, a type of liquid metal. Mercury expands steadily when exposed to heat, and its silvery color makes it easy to see inside the glass tube. Which of the following is true about mercury as a thermometric medium