Identify correct statements 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-dimethylpropane are chain isomers.

Choose the correct answer from the options given below:

Question

Identify correct statements 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-dimethylpropane are chain isomers.

Choose the correct answer from the options given below:

Accepted Answer

A. 1. **Check statement A.** Since propanal (aldehyde) and propanone (ketone) share the molecular formula $\mathrm{C}_3\mathrm{H}_6\mathrm{O}$ but have different functional groups, they are indeed **functional isomers**. Statement A is **true**.

2. **Check statement B.** Given ethoxyethane (diethyl ether) and methoxypropane both have the ether functional group with the same molecular formula but differ in how the alkyl groups are distributed around the oxygen, they are **metamers**. Statement B is **true**.

3. **Check statement C.** Since but-2-ene is a planar alkene with a plane of symmetry and no chiral center, it does **not** show optical isomerism (it shows only cis-trans geometric isomerism). Statement C is **false**.

4. **Check statement D.** Given but-1-ene and but-2-ene both have the same functional group (alkene) differing only in double bond **position**, they are **position isomers**, not functional isomers. Statement D is **false**.

5. **Check statement E.** Since pentane (straight chain) and 2,2-dimethylpropane (branched, same molecular formula $\mathrm{C}_5\mathrm{H}_{12}$) differ in their carbon skeleton, they are **chain isomers**. Statement E is **true**.

**Hence, the correct statements are A, B, and E only — the answer is option A.**