What is the molar concentration of the solution? How many moles of solute are in the solution?What is the molar mass of the solute?

a)
Osmotic pressure, Π = 909/760 atm
Temperature, T = (273 + 27) K = 300 K
Gas constant, R = 0.08206 L atm / (mol K)

van't Hoff formula for dilute solution of non-electrolyte: Π = MRT
Molar concentration of the solution, M = Π/(RT) = (909/760) / (0.08206 × 300) M = 0.0486 M

b)
No. of moles of solute in the solution = (0.0486 mol/L) × (525/1000 L) = 0.0926 mol

c)
Molar mass of the solute = (3.86 g) / (0.0926 mol) = 41.7 g/mol

Let’s use the following equation to determine the number of moles.
P * V = n * R * T

The unit of pressure is atmospheres. One atmosphere is 760 torr.
P = 909/760

The volume must be in liters.
V = 0.525 liter

The exact value of R is 22.4 ÷ 273. Some people round this is 0.0821. To solve this problem the temperature must be converted from °C to °K.

T = 27˚ + 273˚ = 300˚

909/760 * 0.525 = n * (22.4 ÷ 273) * 300
5,107,200 * n = 130,282.425
n = 130,282.425 ÷ 5,107,200

The number of moles is approximately 0.0225. To determine the molar concentration, divide the number of moles by the number of liters.

M = (130,282.425 ÷ 5,107,200) ÷ 0.525

This is approximately 0.0486 mole per liter. To determine the mass of one mole of this compound, divide its mass by the number of moles.

Molar mass = 3.86 ÷ (130,282.425 ÷ 5,107,200)

This is approximately 151 grams. This is the only way that I know how to solve this type of problem. I hope this is helpful for you.