[washey]

The Question states:

Which of the following solutions will have the lowest freezing point?
0.010 m RbI       ( I know this is soluble = Rb + I)
0.010 m K2SeO4 ( I know this is soluble but it disassociates to???)
0.035 m CH3OH  ( I know this is a non-electrolyte and not a choice)
0.015 m SrBr2     ( I know this is soluble = Sr + 2Br)

Can someone direct me to the correct formula?

[DevaDevil]

Freezing point depression is what you need.

All are soluted in the same electrolyte (not necessarily water) I assume, then the one with the highest molality will have the lowest freezing (melting) point

K₂SeO₄ dissociates into 2K⁺ and SeO₄^2-