OAT Optometry Admission Prep Exam Questions & Answers 2026 (11–20)

Question 1

Which reagent would be most appropriate for converting benzaldehyde to benzoic acid?

TheoryPractice · Accepted Answer

$$KMnO_{4}$$. Potassium permanganate ($$KMnO_{4}$$) is a strong oxidizing agent that can oxidize aldehydes to carboxylic acids. It would convert benzaldehyde (C6H5CHO) to benzoic acid (C6H5COOH).

Question 2

What is the major product when 1-bromopropane reacts with sodium hydroxide in aqueous solution?

TheoryPractice · Accepted Answer

1-propanol. When 1-bromopropane reacts with sodium hydroxide in aqueous solution, the hydroxide ion acts as a nucleophile and displaces the bromine atom through an SN2 mechanism, forming 1-propanol.

Question 3

Which of the following pairs represents a set of constitutional isomers?

TheoryPractice · Accepted Answer

Butane and 2-methylpropane. Constitutional isomers have the same molecular formula but different connectivity of atoms. Butane (CH3CH2CH2CH3) and 2-methylpropane ((CH3)3CH) both have the formula $$C_{4}H_{10}$$ but different structures, making them constitutional isomers.

Question 4

Which compound would show the strongest IR absorption band around 1700-1750 cm^-1?

TheoryPractice · Accepted Answer

Acetone. The carbonyl group (C=O) in acetone produces a strong absorption band in the IR spectrum around 1700-1750 cm^-1. This is a characteristic feature of ketones, aldehydes, and other carbonyl-containing compounds.

Question 5

Which of these acids has the LOWEST pKa value (is most acidic)?

TheoryPractice · Accepted Answer

Acetic acid. Acetic acid has the lowest pKa (around 4.8) among these options, making it the most acidic. The carboxylic acid group can donate a proton more readily than the hydroxyl group in ethanol or phenol, and much more readily than the C-H bonds in acetylene.

Question 6

Which of the following best describes the hybridization of the carbon atoms in ethyne (acetylene)?

TheoryPractice · Accepted Answer

sp hybridized with linear geometry. In ethyne (HC≡CH), the carbon atoms are sp hybridized. Each carbon forms a triple bond with the other carbon (one σ and two π bonds) and a single bond with hydrogen, requiring linear geometry with bond angles of 180°.

Question 7

What is the product when cyclohexene reacts with HBr?

TheoryPractice · Accepted Answer

Bromocyclohexane. When cyclohexene reacts with HBr, the reaction follows Markovnikov's rule, where the hydrogen attaches to the carbon with more hydrogens, and the bromine attaches to the carbon with fewer hydrogens. This forms bromocyclohexane.

Question 8

Which type of spectroscopy would be most useful for determining the number and types of hydrogen atoms in an organic molecule?

TheoryPractice · Accepted Answer

1H NMR spectroscopy. 1H NMR (proton nuclear magnetic resonance) spectroscopy is specifically designed to detect hydrogen atoms in different chemical environments. It provides information about the number, type, and arrangement of hydrogen atoms in a molecule.

Question 9

Which statement about resonance structures is correct?

TheoryPractice · Accepted Answer

They represent different electron distributions in the same molecular structure. Resonance structures represent different ways to distribute electrons in a molecule without changing the positions of atoms. The actual structure is a hybrid of all possible resonance forms, contributing to the overall stability of the molecule.

Question 10

What is the expected product when propene reacts with water in the presence of sulfuric acid?

TheoryPractice · Accepted Answer

2-propanol. When propene reacts with water in the presence of sulfuric acid, hydration occurs following Markovnikov's rule. The hydroxyl group attaches to the more substituted carbon (the middle carbon), forming 2-propanol (isopropyl alcohol).

OAT Optometry Admission Prep Exam Questions & Answers 2026 (11–20)

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