What is the main factor that determines how well two substances mix together?

I believe it is density.

Explanation:

Hope this helps!

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

i think its 100

i hope this !