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Quizzes > Science

Chirality Quiz: Practice chiral centers, R/S, and stereochemistry

Quick, free stereochemistry practice to test chiral centers and R/S. Instant results.

Editorial: Review CompletedCreated By: Disciples EdeUpdated Aug 27, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration of molecular models chiral centers stereoisomers enantiomers on teal background

This chirality quiz helps you spot chiral centers, assign R/S configurations, and tell enantiomers from diastereomers. Work through short, exam-style questions with hints and instant feedback to build speed and confidence. For 3D context, try molecular shapes practice, then broaden your review with an organic chemistry quiz.

What does it mean for a molecule to be chiral?
It is superimposable on its mirror image
It has no stereocenters
It cannot be superimposed on its mirror image
It has an internal plane of symmetry
A chiral molecule is one that cannot be superimposed on its mirror image, meaning its mirror image is a distinct object. This non-superimposability arises because the molecule lacks an internal plane of symmetry. Chiral molecules rotate plane-polarized light, a property known as optical activity. .
Which of these molecules possesses a chiral center?
1-Chloropropane (CH3CH2CH2Cl)
cis-2-Butene (CH3CH=CHCH3)
Ethanol (CH3CH2OH)
2-Butanol (CH3CH(OH)CH2CH3)
2-Butanol has a carbon atom bonded to four different substituents (CH3, CH2CH3, OH, H), making it a stereocenter. No other options have a carbon with four distinct groups. Identifying stereocenters is the first step to recognizing chirality in molecules. .
Enantiomers are best described as:
Molecules that are superimposable mirror images
Diastereomers that differ at one stereocenter
Non-superimposable mirror images
Identical molecules with different conformations
Enantiomers are stereoisomers that are non-superimposable mirror images of each other. They have the same physical properties (melting point, boiling point) but rotate plane-polarized light in opposite directions. Enantiomers differ at every stereocenter but share the same connectivity. .
Which of the following statements about meso compounds is true?
Meso compounds are optically active
They exist as enantiomeric pairs
They contain stereocenters but are achiral due to an internal plane of symmetry
They always have only one stereocenter
Meso compounds contain multiple stereocenters but are achiral because they have an internal plane of symmetry that makes them superimposable on their mirror image. As a result, they do not rotate plane-polarized light. They do not form enantiomeric pairs. .
What is a racemic mixture?
A 50:50 mixture of conformers
A mixture of diastereomers
An equal mixture of enantiomers
A single pure enantiomer
A racemic mixture contains equal amounts of both enantiomers of a chiral molecule. Because the optical rotations of the two enantiomers cancel, the mixture is optically inactive. Racemates are often the result of non-stereoselective syntheses. .
According to Cahn - Ingold - Prelog rules, which substituent has the highest priority among the following?
NH2
OH
CH3
F
Under CIP rules, priority is assigned by atomic number: O (8) > N (7) > C (6) > F (9) actually F has atomic number 9, so F would outrank O. Correction: the correct highest priority is F because atomic number 9 > 8. .
How many stereoisomers are possible for 2,3-dibromobutane?
3
2
4
1
2,3-Dibromobutane has two stereocenters, which could give up to 4 stereoisomers, but one is meso, leaving 3 distinct stereoisomers (RR, SS, and meso). The RR and SS pair are enantiomers, and the meso form is achiral. .
A Fischer projection is interchangeable by rotation of the molecule in the plane by:
60°
180°
120°
90°
Fischer projections can be rotated by 180° in the plane without changing the stereochemical configuration. A 90° rotation interconverts substituents incorrectly and is not allowed. Only a half-turn preserves the assignments. .
Which pair of stereoisomers are diastereomers?
R,R and S,S enantiomers
Enantiomers always are diastereomers
R,R and R,S
R,S and S,R (meso)
Diastereomers differ at some but not all stereocenters; for example, R,R and R,S differ at only one center. Enantiomers differ at every stereocenter, while meso forms are identical to their mirror image. .
Which property can be used to differentiate enantiomers?
Refractive index
Melting point
Boiling point
Optical rotation
Enantiomers have identical physical properties such as boiling point, melting point, and refractive index, but they rotate plane-polarized light in equal magnitude and opposite direction. Measuring optical rotation is the primary way to distinguish them. .
Which of the following molecules exhibits axial chirality?
2-Butanol
2,3-Butanediol
1,1?-Binaphthyl
Ethanol
1,1?-Binaphthyl derivatives display axial chirality because rotation around the aryl - aryl bond is restricted, creating non-superimposable mirror images. There are no stereogenic carbon centers involved. This is a classic example of atropisomerism. .
Which of the following compounds is chiral despite lacking a stereogenic carbon atom?
Benzene
1,2-Dichloroethene
Allene with four different substituents
Cyclohexane
A substituted allene with four different substituents on the terminal carbons is chiral due to orthogonal p-orbital geometry, even though no sp3 carbon center is present. The two ?-bonds lock the substituents in a twisted arrangement. Such compounds are optically active. .
What term describes stereoisomers that arise due to restricted rotation around a bond?
Conformers
Enantiomers
Meso compounds
Atropisomers
Atropisomers are stereoisomers that result from restricted rotation around a single bond, often seen in biaryl compounds with ortho substituents. They can be isolated as distinct, stable isomers. They are neither conformers nor enantiomers in the classical sense. .
Which reagent is commonly used to resolve racemic acids by forming diastereomeric salts?
(R)-(-)-2-Butylamine
Methanol
Hydrochloric acid
Sodium hydroxide
Chiral amines such as (R)-(-)-2-butylamine react with racemic acids to form diastereomeric salt pairs that have different solubilities and can be separated by crystallization. After separation, the free acid is recovered. This is a classic resolution technique. .
According to the Cahn - Ingold - Prelog rules, which substituent has higher priority, a vinyl group ( - CH=CH2) or an ethyl group ( - CH2 - CH3)?
Priority depends on conformation
Vinyl group ( - CH=CH2)
They have equal priority
Ethyl group ( - CH2 - CH3)
Under CIP rules, if the first atoms are identical (C vs C), one compares the sets of atoms attached: vinyl carbon is doubly bonded, effectively treated as bonded to two carbons and one hydrogen, while ethyl is bonded to one carbon and two hydrogens. Thus, the vinyl group outranks the ethyl group. .
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Study Outcomes

  1. Identify Chiral Centers -

    Analyze molecular structures to locate chiral centers, reinforcing your chiral center practice and stereochemistry practice skills.

  2. Distinguish Chiral vs Achiral Molecules -

    Compare structural features to determine chirality, improving your chiral vs achiral practice and understanding of molecular symmetry.

  3. Draw Enantiomers -

    Construct accurate mirror-image representations of chiral compounds to master drawing enantiomers and solve chirality practice problems.

  4. Analyze Stereochemistry Relationships -

    Evaluate pairs of stereoisomers to classify them as enantiomers or diastereomers, leveraging stereochemistry practice problems.

  5. Apply R/S Nomenclature -

    Assign R/S configurations to stereocenters systematically, applying stereochemistry practice principles to naming chiral molecules.

  6. Evaluate Your Progress -

    Interpret instant quiz feedback to assess your strengths and target areas for improvement in chirality practice problems.

Cheat Sheet

  1. Identifying Chiral Centers -

    Mastering chirality practice problems starts by spotting sp³ carbons with four unique substituents, following the "all-different rule." Using Cahn - Ingold - Prelog (CIP) priorities from sources like the ACS and IUPAC helps confirm each chiral center reliably.

  2. Assigning R/S Configurations -

    Apply the CIP priority rules, orienting the lowest priority group away, then trace a path from highest to lowest (1→2→3) to determine R (clockwise) or S (counterclockwise). A handy mnemonic is "Right hand rules to the Right," reinforcing R configuration when the path curves clockwise.

  3. Distinguishing Enantiomers vs. Diastereomers -

    In chiral vs achiral practice, enantiomers are non-superimposable mirror images with opposite configurations at every chiral center, while diastereomers differ at one or more but not all centers. For instance, 2,3-butanediol has meso (achiral) and enantiomeric pairs, illustrating stereochemistry practice concepts.

  4. Understanding Racemic Mixtures and Optical Activity -

    In stereochemistry practice problems, a 1:1 mixture of enantiomers (racemate) shows no net optical rotation, while pure enantiomers rotate plane-polarized light in equal and opposite directions. Remember: "Racemic is Rotationally Neutral" to recall its zero net effect (per classical optics references).

  5. Utilizing Fischer Projections -

    Practice chiral center practice by converting wedge - dash formulas into Fischer projections, keeping horizontal substituents toward you and vertical ones away. Use the mnemonic "Horizontal Hands Hold," ensuring correct representation in stereochemistry practice.

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