An organic base (B) has a pKa of 6.950 and a distribution constant (KD), between water and ether, of 3.0. The organic base is extracted from 225 mL of a 0.175 M aqueous solution of B, that has been adjusted to a pH of 8.00, with 75.5 mL of ether. Only one extraction is performed. Calculate the concentration of the organic base (B) in the water phase after the extraction.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.