JEE Advanced2007ChemistrySurface ChemistryActual
Statement I Micelles are formed by surfactant molecules above the critical micellar concentration (CMC). Statement II The conductivity of a solution having surfactant molecules deceases sharply at the CMC.
Options
- AStatement I is true, Statement II is true, Statement II is a correct explanation for Statement I
- BStatement I is true, Statement II is true, Statement II is not a correct explanation for Statement I
- CStatement I is true, Statement II is false
- DStatement I is false, Statement II is true
Correct answer
B. Statement I is true, Statement II is true, Statement II is not a correct explanation for Statement I
Step-by-step solution
At a certain concentration surfactant molecules start to aggregate and form micelle, the concentration is called critical micellisation concentration (CMC). Aggregation of surfactant molecules (ions; RCOO ⁻ ) micelle formation cause effective fall in number of free ions to conduct electricity, thus, conductivity decreases at CMC.