Question

Why mercury is used in clinical thermometer and not water

Answer 1

Mercury is used in clinical thermometer.

• Mercury is the only metal that is in liquid state at room temperature .
• Metals in general expand more than most other materials when heated, which makes it easier to see the difference in temperature which is calibrated, and liquids expand faster than solids.
• Mercury has a high coefficient of expansion which means that a slight change of temperature is noted. As it has a high boiling point, it can be used to measure high temperature too.  

Answer 2

Because of thermal expansion of mercury is expands or contracts at a faster rate than water when its surrounding temperatures change