Why mercury is used in thermometer write in five points?
Liquid in glass thermometers are the cheapest kind of thermometer, and are also easy to use. Mercury is easily the best liquid to use, for 5 important reasons.
1. It is very reflective, so it's easy to see and to read accurately.
2. It doesn't wet the glass, so you don't get inaccurate readings if the temperature is falling.
3. It is a metal, so it's a good conductor of heat. This means that it reacts quickly to changes of temperature.
4. It expands evenly with temperature, so a linear scale can be used with quite a high degree of accuracy.
5. There's a large range of temperature for which it is a liquid. However, it freezes at - 39 Celsius, so Mercury cannot be used below this temperature. It boils at 365 Celsius, which is high enough for most purposes.