Among the following, the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient condition is

Options

A. `(CH_(3))(CH_(2))_(15)N^(+)(CH_(3))_(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 asscoated to form micelle, i.e., lower is the cmc. Hence (a) with the longest. carbon chain has the lowest cmc. [In fact, log (cmc) =A -B (C#)]