Question

why do we use mercury or alcohol as thermometer liquids

Answer 1

as they are metal but they are in liquid form so mercury or alcohol use in thermometer

Answer 2

Mercury is the only one in liquid state at room temperature. It's used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it's used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures.