Identify correct statement from the following: A. Propanal and propanone are functional isomers. B. Ethoxyethane and methoxypropane are metamers. C. But-2-ene shows optical isomerism. D. But-1-ene and but-2-ene are functional isomers. E. Pentane and 2, 2-dimethyl propane are chain isomers. Choose the correct answer from the options given below:

### Core Logic A. Propanal (CH_3CH_2CHO$CH_3CH_2CHO$) and propanone (CH_3COCH_3$CH_3COCH_3$) have different functional groups (aldehyde vs ketone) but the same molecular formula. They are functional isomers. (Correct) B. Ethoxyethane (C_2H_5-O-C_2H_5$C_2H_5-O-C_2H_5$) and methoxypropane (CH_3-O-C_3H_7$CH_3-O-C_3H_7$) differ in the alkyl chains attached to the polyvalent oxygen atom. They are metamers. (Correct) C. But-2-ene shows geometrical isomerism (cis-trans), but no optical isomerism as it lacks a chiral center. (Incorrect) D. But-1-ene and but-2-ene differ in the position of the double bond. They are position isomers, not functional isomers. (Incorrect) E. Pentane (straight chain) and 2,2-dimethyl propane (branched chain) have the same formula C_5H_12$C_5H_{12}$ but different carbon skeletons. They are chain isomers. (Correct) Correct statements: A, B, and E. ### Pattern Recognition Metamerism arises when there is a difference in the alkyl groups attached to a polyvalent functional group (e.g., -O-, -S-, -NH-, -CO-). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Organic Chemistry - Some Basic Principles and Techniques