Structural isomerism and stereoisomerism
- Total number of possible isomers (both structural as well as stereoisomers) of cyclic ethers of molecular formula C_4H_8O is : Answer: 3. 10 Key idea: list all rings of formula C₄H₈O containing O, and count enantiomers/cis-trans. Oxolane (THF): 1. Oxetane with a meth... 1
- Which one of the following compounds can exist as cis-trans isomers? Answer: 4. 1,2-Dimethylcyclohexane Key idea: cis-trans isomerism needs a double bond with different groups on each carbon, or a ring with tw... 1
- The incorrect statement regarding chirality is : Answer: 4. Enantiomers are superimposable mirror images on each other. Key idea: enantiomers are non-superimposable mirror images. Statement... 1
- The compound which shows metamerism is : Answer: 4. C₄H₁₀O Key idea: metamerism occurs between compounds with the same functional group (usually ethers, ketones, secondary amines) b... 1
- Which among the given molecules can exhibit tautomerism? Answer: 4. III only Key idea: keto-enol tautomerism needs an alpha-H, and the enol must be able to form (a double bond at a bridgehead is no... 1
- Which of the following biphenyls is optically active ? Answer: 2. [structure shown in figure] Key idea: a biphenyl is optically active (shows atropisomerism) only if rotation about the central bo... 1