What would be the molar concentration of the solute in each of the following solutions?

a. 0.50 L containing 38.6 g of NaClO4
b. 0.25 L containing 41.5 g of C4H8O

a.

mols NaClO4 = grams/molar mass
Then M = mols/L soln.

b is done the same way.