Why don't thermometers read down to -300 degrees Celsius?

Answer 1

Well, first of all, absolute zero, the point at which there is no thermal energy is at -273 degrees Celsius, so nothing could ever get to -300 C. Also, the Mercury in the thermometer would freeze long before absolute zero, and it is unlikely that a standard thermometer would ever be used below its minimum measurement. If temperature measurement was needed below the minimum measurement of a thermometer, specialized scientific thermometers are available.

Answer 2

Most thermometers are designed to measure temperatures within a specific range, typically from around -50°C to +150°C, because this covers the usual range of temperatures encountered in daily life. To measure extremely low temperatures like -300°C, specialized equipment like cryogenic thermometers or sensors must be used due to the limitations of the materials and technology used in standard thermometers.