A b c or d please help me

What is the molarity of a solution that is prepared by adding 57.1 g of toluene (c 7 h 8 ) (density = 0.867 g/ml) to a 250 ml volumetric flask, and then filling to the mark with benzene (c 6 h 6 ) (density = 0.876 g/ml)?

Fill in the coefficients that will balance the following reaction: a0cr2(so4)3 + a1agno3

Which atom or ion is the largest? a. k b. k+ c. ca d. ca2+ e. li