Final answer:
Alcohol-based thermometers are preferred in extremely low temperatures as alcohol has a lower freezing point than mercury and can function in colder environments. The temperature change results in a noticeable change in the alcohol column of the thermometer.
Step-by-step explanation:
We use alcohol-based thermometers in extremely low temperature regions because alcohol has a lower freezing point compared to mercury, which is commonly used in thermometers. This means that alcohol thermometers can measure temperatures where mercury would be solidified and not function. Moreover, when cold alcohol is placed in a hot liquid, the alcohol initially contracts because the glass expands before the alcohol absorbs heat and expands, causing the column of alcohol to go down slightly before going up.
Key Points on Alcohol-based Thermometers:
• Alcohol expands and contracts more dramatically than the glass encasing it, resulting in a more noticeable change in the thermometer's column length with a small change in temperature.
• The colored alcohol in the thermometer makes it easier to read.
• Alcohol has a much lower freezing point than mercury, allowing it to function in colder temperatures.