In the table above, the two compounds that will combine in the presence of an acid-catalyzed compound, V is

The table lists five organic compounds by their general formulae:

Compound V has the formula RCOOR', which is the general formula for an ester. Esters are produced through a reaction called esterification, in which a carboxylic acid reacts with an alcohol in the presence of a concentrated acid catalyst (typically concentrated \(\text{H}_2\text{SO}_4\)).

The reaction is:

From the table, compound IV (RCOOH) is a carboxylic acid and compound I (ROH) is an alcohol. When these two react together in the presence of an acid catalyst, they undergo a condensation reaction, releasing water and forming the ester RCOOR', which is compound V.

The other pairings do not produce an ester. A ketone (RCOR') lacks the hydroxyl group needed for esterification. An ether (ROR') is relatively unreactive under these conditions and does not participate in ester formation. Only the combination of a carboxylic acid and an alcohol yields an ester through acid-catalyzed condensation.

The correct pair is therefore I and IV.

Exam tip: whenever you see RCOOR' or are asked about ester formation, recall that it always requires a carboxylic acid (-COOH) and an alcohol (-OH) with an acid catalyst, and that water is released as a by-product.