What is one reason why mercury-in-glass thermometers cannot be used at low temperatures?

Mercury-in-glass thermometers cannot be used at low temperatures primarily because mercury freezes at -38.83 degrees Celsius. When temperatures drop to this point or lower, the mercury solidifies, preventing it from expanding or contracting in response to temperature changes. This solidification results in the thermometer being unable to provide accurate readings, as there is no fluid movement to indicate temperature.

Understanding this limitation highlights the importance of the physical properties of substances used in thermometers. Mercury’s freezing point is a critical factor in determining the effective temperature range for these types of thermometers.