Question

Why is water not use in thermometers but rather mercury

Answer 1

Water has different boiling point in different states but Mercury is not like that.

Answer 2

Hey here is your answer....

Water is not helpful to measure below 0oC and above 100oC. The most metals are solids at room temperature but the mercury is liquid form because it has high coefficient of expansion. The mercury does not stick to capillary wall of thermometer and which can easily measure temperature accurately.

Hope it is helpful...