The best thermometer to use where temperatures drop below -39°C (-38.2°F) is:.

The best thermometer to use for this temperature is the alcohol-in-a -glass thermometer.

Explanation:

The alcohol thermometer is a type of thermometer which uses ethanol as its thermometric liquid. This has some advantages at low temperatures because ethanol freezes at about −114.9 °C  that is (−174.82 °F).

Due to its low freezing point, it can still function effectively as a thermometric liquid, expanding and contracting properly based on the applied heat,  when dealing with temperature measurements that are at about -38.2°F.

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.