Final answer:
To convert 1-pentyne into an aldehyde, the correct reagent is c. H₂O₂, H₂SO₄, H₂O, HgSO₄, used in the oxymercuration process of alkynes.
Step-by-step explanation:
To convert 1-pentyne into an aldehyde, reagents must be chosen that can perform oxidative cleavage of the triple bond and stop at the aldehyde stage without further oxidation to a carboxylic acid. Among the options provided (a. 9-BBN, b. NaOH, c. H₂O₂, H₂SO₄, H₂O, HgSO₄, d. NaOH), the correct reagent is c. H₂O₂, H₂SO₄, H₂O, HgSO₄. This reagent combination is used in the oxymercuration process of alkynes to form ketones and aldehydes. Specifically, this process can be used to hydrate terminal alkynes like 1-pentyne to an aldehyde without overoxidizing it to a carboxylic acid.
9-BBN (boron-based reagent 9-borabicyclo[3.3.1]nonane) is typically used in hydroboration-oxidation reactions to convert alkynes to alcohols, while NaOH (sodium hydroxide) is commonly used as a base in various reactions but not typically for this conversion. As NaOH is listed twice and does not contribute to the conversion to an aldehyde for an alkyne, we disregard NaOH in both b. and d. options.