Answer:
a) 36,051.81 g/mol is the molar mass of the protein.
b) The actual molar mass of the protein is 757,087.96 g/mol.
Explanation:
Osmotic pressure of the solution = 
Temperature of the solution , T= 25.0°C=25.0+273 K=298 K
Concentration of solution = C
van't Hoff factor = 20 +1 = 21



Moles of protein = n
Volume of solution = V = 10.0 mL = 0.010 L


Mass of protein = 0.207 g
Molar mass of protein = M
Moles of protein(n) = 

36,051.81 g/mol is the molar mass of the protein.
b)
Actual molar mass of protein = M'
van't hoff factor = 21


The actual molar mass of the protein is 757,087.96 g/mol.