What instrument is used to measure temperature?

Answer: thermometer

Explanation:

Hi, a thermometer is usually a bulb or a spring thermometer. Both work by having a liquid, either alcohol and mercury, enclosed in a vacuum and the liquid expands as the temperature rises. Colored alcohol or mercury rises along a scale in a bulb thermometer whereas expanding liquid rotates a spring to turn an indicator needle around along a circular scale on a spring thermometer. Thermometers now have digital scale displays.