Which compound is an isomer of propanoic acid (CH3CH2COOH)? A)CH2CHCOOH
B)CH3CH2CH2COOH
C)CH3CH(OH)CH2OH
D)HCOOCH2CH3

D) HCOOCH2CH3

Explanation:

An isomer of a compound is defined as a chemical substances with the same formula (That is, same atoms) but in different structures.

For propanoic acid, there are 3 atoms of C, 6 atoms of H and 2 atoms of oxygen.

A) CH2CHCOOH . Here you have 3 atoms of C but 4 atoms of H. That means this compound is not an isomer.

B) CH3CH2CH2COOH . Here, there are 4 atoms of C. Thus, is not an isomer.

C) CH3CH(OH)CH2OH. This structure has 3 atoms of C, but 8 atoms of H. Thus, is not an isomer.

D) HCOOCH2CH3. Here, there are 3 atoms of C, 6 atoms of H and 2 atoms of O. Thus, this structure is an isomer of propanoic acid.

the answer is minerals.