Learn English – ‘At’ vs. ‘on’ when referring to a temperature

prepositions

Assume you have a chemical solution and you want it to be frozen and kept at a temperature of -4 degrees, or you want an action to be taken on the solution at -4 degrees, what would you use then?

Would you write 'freeze at -4 degrees' or 'freeze in -4 degrees',
would you write 'execute the action at -4 degrees' or 'execute the action in -4 degrees'

I know I have kind of answered myself inside my question but I want to know that I'm not mistaken, as I'm writing an academic article and I don't want to hassle my professors with
grammar.

Best Answer

The correct answer would be "execute the action at -4 degrees" because -4 degrees is a point on a large scale.