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12) Which of the following islare eptically lnactive chiral compound enantiomers

ID: 547035 • Letter: 1

Question

12) Which of the following islare eptically lnactive chiral compound enantiomers E3) 3dentify the Solewing compounds as or 14) What is the relationship between the following compounds? 14 A) enantiomers 11) superimposable without bond rotatiorn C) constitutional isomens D) confornmational isemers b) diastereomers 15) Which of the following is a true statement? 15) A) All molecules which possess two or more chirality centers will be chirai B) All chiral molecules possess a plane of symmetry C) All achiral molecules are meso. D) All molecules which possess a single chirality center ol the S coefigurntion ane levorotabory E) A mixture of achiral compounds will be optically inactive. 16) How many stereoisomers exist with the following basic connectivity? 16) BrCH2CH(CHsXCH2CH3 A) 0 B) 1 C)2 0) 4 E 8 17 17) The specific rotation of a pure substance is -5,90°. What is the percentage of this isomer in a mixture with an observed specific rotation of -2.95? C)25% D)0% E)80% A)50% B) 75%

Explanation / Answer

12) Ans - all of the above

To be optically active, the compound must be chiral and should not have mirror plane symmetry. Thus, compounds which is achiral are optically inactive. Moreover, meso compound have internal mirror plane symmetry such that one half becomes the mirror image of other and hence, optical rotation due to one half gets canceled by the other. In case of racemic mixture and 50-50 mixture of the R and S isomers are also optically in active, as, rotation due to one half gets canceled out due to other and hence net rotation becomes zero.