19.Which of the following cyclic alkanes can be ring-opened under hydrogenation conditions H, eyelic hydrocarbon linear hydrocarbon Pd A)cyclopropane D)cyclohexane cyclobutane E)more than one of these C cyclopentane Ans: 20.Which of the following statements about conformations of methyleyelohexane is true? CHs AN CH A)The energy barrier to interconvert these is too high to be achieved at room temperature. 9 The two forms are in equilibrium and are present in equal amounts at room temperature. The two forms are not in equilibrium but are present in equal amounts at room D) emperatu ms are in equilibrium but are not present in equal amounts at room atur E)The two forms are not in equilibrium and are not present in equal amounts at room temperature. Ans:D 21.Cyclohexanes exhibit a higher than their straight-chain analogs.(Choose the D) All of these R e are co of the se are correc Ans:D .Which conformation of cyclohexane exprinc thmon A) Chair B)Planar C)Boat E)All of these are Page 9Page 9 19. Which of the following cyclic alkanes can be ring-opened under hydrogenation conditions? cyclic hydrocarbon H2 Pd linear hydrocarbon A) cyclopropane D) cyclohexane B) cyclobutane E) more than one of these C) cyclopentane Ans: E 20. Which of the following statements about conformations of methylcyclohexane is true? CH3 CH3 A) The energy barrier to interconvert these is too high to be achieved at room temperature. B) The two forms are in equilibrium and are present in equal amounts at room temperature. C) The two forms are not in equilibrium but are present in equal amounts at room temperature. D) The two forms are in equilibrium but are not present in equal amounts at room temperature. E) The two forms are not in equilibrium and are not present in equal amounts at room temperature. Ans: D 21. Cyclohexanes exhibit a higher_______than their straight-chain analogs. (Choose the correct answer) A) boiling point D) All of these are correct. B) melting point E) Two of these are correct. C) density Ans: D 22. Which conformation of cyclohexane experiences the most transannular strain? A) Chair B) Planar C) Boat D) Twist boat E) All of these are stable. Ans: C