In each of the four molecules shown below the oxygen atom has two lone pairs of electrons to complete its Octet. HH H T || H-C-C-0-H H ## Η Η Α H B H H H-C-C-H H-C-O- | | ннс -C-H HD H Which of these molecules could function only as a hydrogen bond acceptor? A and B A B and C and D B and C all four could

Formula Lewis Electron Molecular Bond Polar or Attractive Structure Pair Geometry Angle Force Non Polar Geometry Between Molecules CH4 Around First C Around First C C2H4 Around First C Around First C C,H2 Around First C Around First C CH;OH Around O Around O C2H;OH Around O Around O CH20 CH,OCH, Around O Around O CH;COOH Central C Central C НСООН Central C Central C CH;NH2 Around N Around N CH;COCH; Central C Central C

Rank the elements or compounds in the table below in decreasing order of their boiling points. That is, choose 1 next to the substance with the highest boiling point, choose 2 next to the substance with the next highest boiling point, and so on. substance A B C D H chemical symbol, chemical formula or Lewis structure H | HC H | N H- HIC - C C - H Η H HIC C I | H H — — - H Cr O-H Ar :O: O HIC - H C H - H - X boiling point (Choose one) ◊ (Choose one) (Choose one) (Choose one) ✪ S

Choose the least polar bond using electronegativities. F - 4.0 O - 3.5 N - 3.0 Cl - 3.0 S - 2.5 I - 2.5 P - 2.1 Li - 1.0 Na - 0.9