Molarity is defined as:
Number of moles of solute (KI) per liter of solution (KI + water)
We also need the molar mass of KI, equal to 166 g/mol
Procedure:
The number of moles of KI = 2.08 g/166 g/mol = 0.0125 moles KI
Volume = 279 mL = 0.279 L (1 L = 1000 mL)
Therefore,
0.125 moles KI ------- 0.279 L of solution
X ------- 1 L of solution
X = 0.448 mol/L
Another procedure:
Molarity = number of moles (KI)/Volume of solution (L)
Molarity = 0.125 moles/0.279 L = 0.448 mol/L or M
Answer: M = 0.448 mol/L