What is a thermometer? What is a gas thermometer? Write its characteristics.

(N/A) thermometer is a device used to measure the temperature of a system or a body. It works on the principle that certain physical properties of substances change with temperature.
$A$ gas thermometer is a type of thermometer that uses the change in pressure or volume of a gas at a constant volume or constant pressure,respectively,to measure temperature. It is based on the ideal gas law,$PV = nRT$.
Characteristics of a gas thermometer:
$1$. It is highly accurate and is often used as a standard for calibrating other thermometers.
$2$. It has a wide range of temperature measurement,typically from very low temperatures (near absolute zero) to very high temperatures.
$3$. It is based on the properties of an ideal gas,which makes it independent of the specific material properties of the container.
$4$. It is generally bulky and slow to respond to temperature changes compared to liquid-in-glass thermometers.