23.Which structure is different from the others? CHCHCICHICH C-CH3 D 3 CH5-CH CI-CH-CH3 及alre enteal geosmin? (-)-geosmi A)C1H200B)C12H220 C)CuH21O D)C12H20O E)C12H21O Ans:B carbo-carbn bondsndicaed od you expettobthonges A)A B)B C)C D)D E)E Ans:D Page 10 Page 10 23. Which structure is different from the others? A) Cl B) CH3CHClCH(CH3)2 C) CH3 C C Cl CH3 H3C H H D) CH3 CH CH CH3 Cl CH3 E) all are identical Ans: E 24. A fairly common algal metabolite is the compound (-)-geosmin, which imparts a musty odor to water even at concentrations in the ppb range. What is the molecular formula of geosmin? (-)-geosmin CH3 HO CH3 A) C11H20O B) C12H22O C) C11H21O D) C12H20O E) C12H21O Ans: B 25. Which of the carbon-carbon bonds indicated would you expect to be the longest in stilbene? A B C D E A) A B) B C) C D) D E) E Ans: D