If you were preparing 1 mole of the mixture, you would have taken 0.8 moles of DDS + 0.2 moles of ODS (4: 1). KKM DDS 0.008 mol / l. Octyl sulfate will reduce the CMC of the mixture. You must take a concentration greater than CMC DDS, for example, 0.01 mol / l and 0.0025 ODS (4: 1)

Thank you sir for answering. Should we consider the moles of water present in aqueous solution while calculating the mole fraction of surfactants as the basic definition of mole fraction demands so? What is meant by alpha surfactant, a term in general use in the research papers?

0.008 mol / l water. What is meant by alpha surfactant, a term in general use in the research papers? I did not see this.

Alpha represents the location of an atom or molecule in the chemical formula. e.g. sodium alpha olefin sulfonate surfactant will have sodium atom located at first carbon atom. If its beta then it is attached to second carbon atom...likewise. It is called as Internal olefin sulphonate if molecule is located to internal carbon atom.@ Farah Ansari

@Amita Kosambi. Alpha represents the location functional group (-OH, -NH2 ...) in the chemical formula. The sodium atom does not form bonds with the carbon atoms of the surfactant. "alpha surfactant" There is no such name in decent scientific literature.

@ Yuri Mirgorod, thank you for the correction. It should be sulfonate group attached to the alpha caron atom of surfactant. And not a sodium atom. R-CH=CH-(CH2)n-SO3Na Sodium alpha olefin sulfonate. There may not be a exact term of alpha surfactant but I guess it is used for alpha olefin sulfonate surfactant.