Question

At Low temperatures _____ type of thermometer is used.
(A) Mercury Thermometer
(B) Water thermometer
(C) Alcohol thermometer
(D) Thermometers cannot be used

Answer 1

Although most of the thermometers can be used at varying temperatures, there are a few limitations. The limitations of the thermometer that does not allow it to measure temperature of a body at a considerably lower temperature corresponds to the freezing point of the liquid that is used in the thermometer.

Complete answer:
Heat is a form of energy and temperature is a measure of heat. Thus, temperature is a measure of energy possessed by the body in the form of heat. A thermometer is nothing but a universal instrument that is used to measure temperature. Usually the measurements are done in Celsius $\left( {^\circ C} \right)$ and Fahrenheit $(^\circ F)$. Although the SI unit of temperature is Kelvin $(K)$.
There are different kinds of thermometers according to their needs. The only difference that each type of thermometer might possess will be the liquid that is used in them. The most commonly used clinical thermometers (the ones that you used to check your body temperature) have mercury in it and are hence also called as a Mercury thermometer. The mercury thermometer usually has a range of $35^\circ c$ to $42^\circ c$. Since the conditions that they work in are only to measure the body temperature, which is normally $32^\circ c$.
Just like that each type of thermometer has a different liquid chosen according to the conditions they work in and the freezing point of that liquid.

The freezing point/melting point of Mercury is $- 38.83^\circ c$.
The freezing point of water is $0^\circ c$.
The freezing point of alcohol is $- 114.9^\circ c$.
Since Alcohol has the lowest freezing point, it can be used comfortably in lower temperatures.
Hence the correct answer is option (C).

Note:
When we say Alcohol, we will be naming a chemical compound but in thermometers we use Ethanol or Ethyl Alcohol $({C_2}{H_5}OH)$. Most of the time Ethanol is interchangeably used with the name “Alcohol”. And it is Ethanol that is used in the Alcohol thermometer. It is also the component of your alcoholic drinks.