What is mercury
what is clinical thermometer

What is labrotary thermometer

The explanation for your question is as follows.

Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum

A clinical thermometer is a thermometer used to measure human body temperature. Most old ones use mercury thermometer. It is accurate and sensitive, because it has a narrow place where the mercury level rises very fast.
These thermometers are used in clinics by doctors, so they are also called a doctor's thermometers or medical thermometers. Most of them show both Celsius scale and Fahrenheit temperature scales. The scale runs from 35 degree Celsius to 42 degree Celsius.

A laboratory thermometer is a tool used in laboratories to measure temperature with high accuracy. It can be partially or fully immersed in the substance being measured. A laboratory thermometer is recognizable by its long stem with a silver bulb at the end.

These days many thermometer used are digital, that is they do not use mercury.

Hope it answers your question.
All the best!