Which device is used to measure the air temperature of a room?

The device used to measure the air temperature of a room is a thermometer. Thermometers function by indicating the temperature through various means, such as the expansion of a liquid (like mercury or colored alcohol) or the change in electrical resistance with temperature variations. This makes them essential tools in both residential and commercial settings for ensuring comfortable indoor climates.

On the other hand, a thermostat is primarily used for regulating the temperature within a certain range, rather than measuring it directly. A barometer measures atmospheric pressure, which is important for weather prediction but not for direct temperature measurement. A remote control is a device for operating other devices wirelessly but has no role in measuring temperature. Thus, the thermometer is the correct answer for measuring the air temperature in a room specifically.