Am I Ready for the ACS Organic? Free 25-Question Quiz

Published 2026-11-04 · Facts and text checked 2026-11-02 · Questions from our ACS Organic study guide · Reviewed by Hana N., Quality Reviewer

Take this free 25-question ACS Organic readiness quiz and see your score, a verdict of ready, almost or not yet, and the topics to study next. The questions come from our ACS Organic study guide and are corrected when you finish. No account is needed, and the verdict is our study target, not an official score.

Question 1 of 25

Which statement best describes the stereochemical outcome of an SN1 reaction that begins with a single enantiomer of a chiral alkyl halide?

A.A racemic mixture is formed, sometimes with a slight excess of inversion.B.Complete inversion of configuration occurs.C.Complete retention of configuration occurs.D.A racemic mixture is always formed in an exactly 50:50 ratio.

Question 2 of 25

A chemist treats 5-hydroxyhexan-2-one with methylmagnesium bromide, expecting to convert the ketone into a tertiary alcohol. What is the most likely outcome?

A.The reaction forms a cyclic acetal insteadB.The Grignard reagent adds to the ketone, giving the expected tertiary alcoholC.The Grignard reagent reduces the ketone to a secondary alcoholD.The Grignard reagent is protonated by the hydroxyl group, so the ketone is not attacked

Question 3 of 25

3-Methyl-1-pentene reacts with HBr. After a hydride shift, what is the major product?

A.3-bromo-3-methylpentaneB.2-bromo-2-methylpentaneC.2-bromo-3-methylpentaneD.3-bromo-2-methylpentane

Question 4 of 25

Which of the following compounds should show the most downfield methyl proton signal in its 1H NMR spectrum?

A.Ethane (CH3CH3)B.Methane (CH4)C.Chloromethane (CH3Cl)D.Toluene (C6H5CH3)

Question 5 of 25

Which structural feature most directly accounts for the unusually high enol content of 2,4-pentanedione compared with a simple ketone?

A.The enol has a tertiary alcohol, which is more stable than a secondary alcoholB.The keto tautomer contains a highly strained four-membered ringC.The enol is stabilized by an intramolecular hydrogen bond that forms a six-membered ringD.The enol is aromatic because of extended conjugation

Question 6 of 25

A student suggests adding a sulfonic acid group to toluene at the para position as a blocking group to force the next electrophile to the para position. Why is this suggestion incorrect?

A.The sulfonic acid group is too small to block the para position.B.The para position becomes occupied, so the next electrophile is forced to an ortho position, not the para position.C.The sulfonic acid group would convert the methyl group into a meta-directing group.D.The sulfonic acid group is removed too easily under the reaction conditions.

Question 7 of 25

Two valid resonance contributors have identical atom positions and complete octets on every atom. Contributor 1 has no formal charges; Contributor 2 has a +1 charge on one atom and a -1 charge on another. Which statement correctly ranks the contributors?

A.Contributor 2 is the major contributor because it has both a positive and a negative charge.B.Both contribute equally because they are valid resonance contributors.C.Contributor 1 is the major contributor because structures with fewer formal charges are more significant.D.Contributor 2 is the major contributor because charge separation stabilizes a resonance hybrid.

Question 8 of 25

A ketone must be protected before a reaction that is run in concentrated sulfuric acid at 100 °C. Why is a cyclic acetal a poor choice?

A.Acetals react with sulfuric acid to form explosive productsB.Acetals are stable to acid and would not be removed at the endC.Acetals are only stable under basic conditions, so they would decompose before the acid stepD.Acetals are hydrolyzed under strongly acidic conditions, so the ketone would be unmasked prematurely

Question 9 of 25

Which statement correctly compares a methyl radical, •CH3, with a primary radical such as •CH2CH3?

A.Methyl radical is more stable because it is less substituted and therefore less sterically strained.B.Primary radical is more stable because the adjacent C-H sigma bonds can donate electron density into the singly occupied orbital.C.The two radicals are equally stable because both have an unpaired electron on carbon.D.Primary radical is more stable only when the radical carbon is part of a ring.

Question 10 of 25

Two enantiomers of a chiral compound are dissolved separately in the same achiral solvent at identical concentrations. Which property will differ between the two solutions?

A.boiling pointB.refractive indexC.solubility in the solventD.the direction of rotation of plane-polarized light

Question 11 of 25

For an acid-base reaction, the equilibrium constant is calculated as K = 10 raised to the power (pKa(acid on product side) - pKa(acid on reactant side)). If the exponent is negative, which statement about the equilibrium is correct?

A.K > 1, and the products are favoredB.K = 1, and the reaction is at equilibriumC.K < 1, and the reactants are favoredD.K cannot be determined from the sign alone

Question 12 of 25

For a linear conjugated polyenyl system with five p orbitals, which statement about the node pattern in its pi molecular orbitals is correct?

A.The lowest-energy orbital has one node, and each higher orbital gains one additional node.B.The orbitals have 0, 1, 2, 3, and 4 nodes, and the nonbonding orbital has two nodes.C.The nonbonding orbital has three nodes, and the orbital immediately below it has two nodes.D.The orbital of highest energy has four nodes, and the nonbonding orbital has one node.

Question 13 of 25

Which is the major organic product of the E2 reaction of 2-bromo-2-methylbutane with potassium ethoxide in ethanol?

A.2-methyl-1-buteneB.2-methyl-2-buteneC.2-methylbutaneD.3-methyl-1-butene

Question 14 of 25

What explains why an ester is less reactive than a ketone toward nucleophilic addition at the carbonyl carbon?

A.The alkoxy oxygen donates a lone pair into the carbonyl pi system, and the resulting resonance gives the C-O bond partial double-bond character and reduces the electrophilicity of the carbonyl carbon.B.The ester carbonyl oxygen is less basic than the ketone carbonyl oxygen, so protonation is unfavorable.C.The alkoxy group withdraws electron density by induction, making the carbonyl carbon more electrophilic.D.The carbonyl carbon is sp3 hybridized, so it cannot undergo nucleophilic addition.

Question 15 of 25

Hydroboration-oxidation of propene gives which major organic product?

A.propanalB.2-propanolC.1,2-propanediolD.1-propanol

Question 16 of 25

Which functional group is indicated by a strong carbonyl absorption at 1650 cm-1 together with a medium N-H stretch near 3300 cm-1?

A.EsterB.AmideC.KetoneD.Acid chloride

Question 17 of 25

When an aldol addition product is heated, the characteristic transformation is:

A.Decarboxylation to form a shorter-chain ketoneB.Dehydration to form a conjugated enoneC.Tautomerization to the more stable enol formD.Intramolecular cyclization to a lactone

Question 18 of 25

Which statement most accurately explains why toluene undergoes nitration faster than benzene and directs the nitro group to ortho and para positions?

A.The methyl group withdraws electron density by resonance, making the ring more electrophilic.B.The methyl group stabilizes the sigma complex through hyperconjugation, which lowers the activation energy for attack at ortho and para positions.C.The methyl group donates a lone pair into the ring, increasing electron density equally at all positions.D.The methyl group releases electron density through induction, but this speeds up attack at all positions equally without changing the product distribution.

Question 19 of 25

Sulfur dioxide, SO2, has two S-O double bonds and one lone pair on sulfur. Which molecular geometry describes the arrangement of the oxygen atoms around sulfur?

A.Trigonal planarB.Trigonal pyramidalC.BentD.Linear

Question 20 of 25

A ketone in a polyfunctional molecule is protected as a cyclic acetal so that a Grignard addition can be performed at a different site. Which planned next step would make the acetal protecting group unusable?

A.Hydrogenation of an alkene over palladium on carbonB.Treatment with lithium aluminum hydride in etherC.SN2 displacement of a primary bromide with sodium cyanide in DMSOD.Acid-catalyzed esterification of a remote carboxylic acid with methanol

Question 21 of 25

2-Methylbutane has 9 primary, 2 secondary, and 1 tertiary hydrogens. For radical bromination, the relative abstraction rates are primary:secondary:tertiary = 1:80:1600. Which statement best describes the predicted monobromination mixture?

A.The primary monobromide is the major product because there are nine primary hydrogens.B.All three monobromides are formed in roughly comparable amounts.C.The secondary monobromide is the major product because the secondary rate, 80, is halfway between the other rates.D.The tertiary monobromide accounts for about 90 percent of the mixture, and the primary monobromide is a trace.

Question 22 of 25

Which statement best explains why the fully eclipsed conformer of butane, in which the two methyl groups eclipse each other, is about 16 kJ/mol less stable than the anti conformer, whereas the gauche conformer is only about 3.8 kJ/mol less stable?

A.The fully eclipsed conformer is less stable only because its C-H bonds are forced into an eclipsed arrangement that lacks any steric repulsion.B.The fully eclipsed conformer has both torsional strain and direct steric repulsion between the methyl groups, whereas the gauche conformer has only modest steric repulsion and no torsional strain.C.The energy difference is due to a change in bond angle strain, not to any interaction between methyl groups.D.The gauche conformer is staggered but has more torsional strain than the fully eclipsed conformer.

Question 23 of 25

A table of pKa values measured in water at 25 °C includes water itself (pKa 15.7), acetic acid (pKa 4.8), ethanol (pKa 16.0), and ammonia (pKa 38). Based on these values, which statement is correct?

A.Water is the strongest acid in the tableB.Ammonia is a stronger acid than waterC.Ethanol is a stronger acid than waterD.Acetic acid is a stronger acid than water

Question 24 of 25

An electron-withdrawing substituent on a dienophile accelerates a Diels-Alder reaction. Which molecular-orbital change best explains this acceleration?

A.The substituent lowers the dienophile's LUMO energyB.The substituent raises the dienophile's HOMO energyC.The substituent lowers the diene's LUMO energyD.The substituent raises the diene's HOMO energy

Question 25 of 25

A chemist measures the initial rate of an E2 reaction and then repeats it with the concentration of the base doubled while keeping the substrate concentration the same. If the reaction follows E2 kinetics, how does the rate change?

A.It is unchanged.B.It halves.C.It doubles.D.It quadruples.

Answer at least 15 questions to get a verdict.

How the verdict works: 80% or more correct = ready, 65-79% = almost, below 65% = not yet. It is a conservative bar for practice, not the official passing score. The questions are corrected on our server; none of them appears with its answer on our other ACS Organic pages.

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