4 . D
Each mole of H 3 PO 4 contains 3 moles of hydrogen and (since this is an acid) three equivalents.
A 2 M solution of this acid is thus 2 M × 3 N/M = 6 N.5 . 64.4
The number of moles of water is found by estimating the density of water to be 1 g/mL.
If the mole fraction of ethyl alcohol is to be 0.2, then the mole fraction of water must be 0.8. If
n equals the total number of moles:Thenmol ethyl alcohol = (.2)(7) = 1.4 mol
and(1.4 mol ethyl alcohol) (46 g/mol) = 64.4 g ethyl alcohol6 . B
Only ionic compounds (electrolytes) dissolved in polar solvents will conduct electricity. Sugar
is a covalent solid, and therefore is not an electrolyte even when dissolved in water. Choice C is
incorrect because salt will not dissolve appreciably in an organic solvent and so no ions will be
present. Choice D is incorrect because oil and water are immiscible, and neither on its own
contains a significant amount of electrolytes. Salt water is in essence an aqueous solution of
NaCl, which dissociates to generate Na+ and Cl– ions, and so choice B is correct.