Question

Calculate the molarity of a solution in which 0.75 moles of a solute are dissolved in 125g of solution (density of solution = 1.05g/mL).

I did this much:
1.05 * 1L/1000mL = 0.001 L

I don't really know what to do.

Answer 1

What you did isn't much help. I don't understand it.
molarity = mols/L of solution.
you know mols. Use the density to convert 125 g solution to volume (liters) of solution.

Answer 2

v = m/d
v = 125g/1.05 g/mL
v = 119.mL

Then I converted mL to L
119 mL x 0.001 L/1mL = 0.119 L

Then,
M = mol/L
M = 0.75 mol/0.119 L
Final answer: 6.3 mol/L

Answer 3

That's my answer, too.