Asolution of 1.50g of solute dissolved in 25.0 ml of h2o at 25c has a boiling point of 100.95c. what is the molar mass of the solute if it is a nonvolatile non electrolyte and the solution behaves ideally. (d of h2o at 25c=0.997g/ml)?

If you had followed the directions I think you would have ended up with the right answer since the only difference is in what is used for K. Kf for freezing point is 1.86 and Kb for boiling point is 0.512 
Here is how it's done. 

mass H2O = volume x density = 25.0*0.997 = 24.925 g 
delta T = Kb*m 
100.95-100 = 0.95 = 0.512*m 
(Note: Use the Kb in your text/notes. 0.512 is in my notes but I often see 0.52 used.) 
Solve for m and I have 1.855. 
m = mol/kg solvent 
1.855m = moles/0.024925 
mols = 1.855 x 0.024925 = 0.04625 
mol = g/molar mass so 
molar mass = grams/mol = 1.50/0.04625 = 
32.43 which I would round to 32.4 to 3 significant figures. You should confirm these numbers. If I round earlier I get 32.5. Let me know if you have questions. I suspect you used T (100.95) as delta T.

A.