Write a mechanism for the conversion of the aldol addition product, 3-hydroxy-3-(4-nitrophenyl)-1-(2-py ridyl)-1-propanone, to the aldol condensation product, (E)-3-(4-nitrophenyl)-1-(2-pyridyl) -1-propenone. Be as complete as possible and show electron flow for all steps.

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.