Final answer:
An infrared thermometer is commonly used to check the temperature of food on a serving line because it is quick, accurate, and sanitary.
Step-by-step explanation:
The type of thermometer commonly used to check the temperature of chicken and food on a serving line is an infrared thermometer. This device measures the infrared radiation emitted by objects, which varies with temperature, allowing for a quick and accurate temperature readout. This method of temperature measurement is more accurate and sanitary compared to other types such as oral or mercury thermometers, which require physical contact. Infrared thermometers are especially useful in settings where food safety is paramount and quickly verifying that food has reached a safe temperature is necessary.