Question

Alcohol thermometers are preferred to a mercury thermometer in cold countries. Explain.

Answer 1

Thermometer:

1. The instrument used to measure temperature is called thermometer.
2. The principle of expansion of liquids with rise in temperature is used to measure temperature in thermometer.
3. If the liquid used in thermometer freezes, the reading will be incorrect.
4. The mercury thermometer uses the mercury as the thermometric liquid, mercury has a higher freezing point compared to alcohol.
5. Hence, mercury will easily freeze (freezing point of mercury is $-{39}^{0}C$).
6. The alcohol thermometer uses the alcohol as the thermometric liquid.
7. While the alcohol has lower freezing point than mercury ((freezing point of alcohol is $-{115}^{o}C$).
8. Thus, alcohol thermometers are preferred to a mercury thermometer in cold countries.