Among the following, which surfactant will form micelles in aqueous solution at the lowest molar concentration at ambient conditions?

Options

A. `CH_(3)(CH_(2))_(15)N^(+)CH_(3)Br^(-)`
B. `CH_(3)(CH_(2))_(11)OSO_(3)^(-)Na^(+)`
C. `CH_(3)(CH_(2))_(6)COO^(-)Na^(+)`
D. `CH_(3)(CH_(2))_(11)N^(+)(CH_(3))_(3)Br^(-)`

Answer

A

Explanation

Longer the carbon chain, i.e., greater is the size of the hydrophobic chain (tail), less is the solubility in water and greater is the tendency of surfactant molecules to associate to form micelle, i.e., lower is the C.M.C . Hence (A) with the longest carbon chain has the lowest C.M.C.