JEE Main 2015 · 11 Apr · Shift 1 · Chemistry Q40

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ChemistrySingle correct+4 / -1Question 40 of 90

Under ambient conditions, which among the following surfactants will form micelles in aqueous solution at lowest molar concentration ?

\ce{CH3(CH2)15N+(CH3)3Br-}

\ce{CH3-(CH2)13-OSO3^- Na+}

\ce{CH3-(CH2)8-COO^- Na+}

\ce{CH3(CH2)11N+(CH3)3Br-}

Answer and worked solution

Official answer: A

The critical micelle concentration falls as the hydrophobic chain lengthens. The C₁₆ quaternary ammonium salt has the longest chain, so it forms micelles at the lowest concentration.

Topics:Colloids

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JEE Main 2015 · 11 Apr · Shift 1, Chemistry question 40