CUET UG Chemistry Booster Test - 2 Introduction & Nomenclature (Aldehydes and Ketones) -

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CUET UG Chemistry Booster Test - 2 Introduction & Nomenclature (Aldehydes and Ketones)

⏱️ 30 Minutes

❓ 20 Questions

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Chemistry Booster Test - 2 Introduction & Nomenclature (Aldehydes and Ketones)

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QUESTION 1 OF 20

Consider the basic structure of the carbonyl group:
1. The carbon-oxygen double bond is polarised due to higher electronegativity of oxygen relative to carbon.
2. Carbonyl carbon acts as a nucleophilic (Lewis base) center.
3. Carbonyl compounds possess substantial dipole moments.

Answer Review

1 Consider the basic structure of the carbonyl group:
1. The carbon-oxygen double bond is polarised due to higher electronegativity of oxygen relative to carbon.
2. Carbonyl carbon acts as a nucleophilic (Lewis base) center.
3. Carbonyl compounds possess substantial dipole moments.

A 1 and 2

B 1 and 3

C 2 and 3

D 1, 2 and 3

💡 Short Explanation

�� Oxygen is more electronegative than carbon. �� Carbonyl carbon is electrophilic. �� Carbonyl compounds possess significant dipole moments.

✅ Correct Answer Explanation

The C=O bond is strongly polar because oxygen is more electronegative than carbon. This creates a partial positive charge on carbon and a partial negative charge on oxygen, giving carbonyl compounds substantial dipole moments. Therefore, the carbonyl carbon acts as an electrophilic center rather than a nucleophilic center.

❓ Why Other Options Are Incorrect

�� Statement 2 is incorrect because carbonyl carbon is electrophilic.
�� Options A, C and D include statement 2.

🎯 Strategy

Used

Elimination

Application:

�� Identify the incorrect statement regarding carbonyl reactivity.

Final Logic:

�� Statements 1 and 3 are correct.

🧠 Memory Trick

Cδ⁺ = Electrophile, Oδ⁻ = Nucleophile.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Nature of Carbonyl Group

2 In which specific class of functional groups is the carbonyl carbon bonded to halogens?

A Acyl halides

B Amides

C Esters

D Ketones

💡 Short Explanation

�� Acyl halides contain the –COX group. �� X represents a halogen atom. �� Carbonyl carbon is directly bonded to halogen.

✅ Correct Answer Explanation

Acyl halides have the general formula R–COX, where X is a halogen such as Cl, Br or I. Therefore, the carbonyl carbon is directly attached to a halogen atom.

❓ Why Other Options Are Incorrect

�� Option B → Carbonyl carbon bonded to nitrogen.
�� Option C → Carbonyl carbon bonded to oxygen.
�� Option D → Carbonyl carbon bonded to carbon atoms.

🎯 Strategy

Used

Functional Group Identification

Application:

�� Examine atoms attached to the carbonyl carbon.

Final Logic:

�� Only acyl halides contain a carbonyl carbon bonded to halogen.

🧠 Memory Trick

Acyl halide = COX.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Carbonyl Derivatives

📄 Passage

The carbonyl carbon atom is sp²-hybridised and forms three sigma (σ) bonds. The fourth valence electron of carbon remains in its p-orbital and forms a π-bond with oxygen by overlap with a p-orbital of oxygen.

What type of bonds connect the carbonyl carbon to its adjacent atoms in an aldehyde group?

A Four sigma bonds

B Three sigma bonds and one pi bond

C Two sigma bonds and two pi bonds

D One sigma bond and three pi bonds

💡 Short Explanation

�� Carbonyl carbon is sp² hybridised. �� It forms three σ bonds. �� One π bond forms the C=O bond.

✅ Correct Answer Explanation

The carbonyl carbon forms three sigma bonds using sp² hybrid orbitals and one pi bond through sideways overlap of p-orbitals with oxygen. Thus, the carbonyl group contains three σ bonds and one π bond around the carbonyl carbon.

❓ Why Other Options Are Incorrect

�� Option A → Ignores the π bond.
�� Option C → Carbonyl contains only one π bond.
�� Option D → Impossible bonding arrangement.

🎯 Strategy

Used

Passage-Based Analysis

Application:

�� Use the bonding description provided.

Final Logic:

�� Carbonyl carbon forms 3σ + 1π.

🧠 Memory Trick

C=O = 1σ + 1π.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Structure of Carbonyl Group

📄 Passage

The carbonyl carbon and the three atoms attached to it lie in the same plane and the π-electron cloud is above and below this plane.

Where does the π-electron cloud reside relative to the plane containing the carbonyl carbon and its three attached atoms in a ketone?

A Only above the plane

B Only below the plane

C Above and below the plane

D Within the same plane

💡 Short Explanation

�� π bond arises from p-orbital overlap. �� Electron density lies on both sides of the plane. �� Characteristic of trigonal planar carbonyl groups.

✅ Correct Answer Explanation

The π bond is formed by sideways overlap of p-orbitals. As a result, the π-electron cloud exists above and below the plane containing the carbonyl carbon and the three atoms attached to it.

❓ Why Other Options Are Incorrect

�� Options A and B represent only half of the π cloud.
�� Option D is incorrect because π electrons are not located in the plane.

🎯 Strategy

Used

Passage-Based Analysis

Application:

�� Apply p-orbital overlap concept.

Final Logic:

�� π-electron cloud exists above and below the plane.

🧠 Memory Trick

π bond = Electron cloud on both sides.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Structure of Carbonyl Group

5 Match the natural plant source with its respective extracted aldehyde:

List-I	List-II
1. Vanilla beans	a. Salicylaldehyde
2. Meadow sweet	b. Cinnamaldehyde
3. Cinnamon	c. Vanillin

A 1-c, 2-a, 3-b

B 1-a, 2-b, 3-c

C 1-b, 2-c, 3-a

D 1-c, 2-b, 3-a

💡 Short Explanation

�� Vanilla beans → Vanillin. �� Meadow sweet → Salicylaldehyde. �� Cinnamon → Cinnamaldehyde.

✅ Correct Answer Explanation

Plant Source — Aldehyde Vanilla beans — Vanillin Meadow sweet — Salicylaldehyde Cinnamon — Cinnamaldehyde Therefore: 1-c, 2-a, 3-b

❓ Why Other Options Are Incorrect

�� Options B, C and D contain incorrect pairings.

🎯 Strategy

Used

Matching Analysis

Application:

�� Recall naturally occurring aldehydes.

Final Logic:

�� Vanilla–Vanillin, Meadow sweet–Salicylaldehyde, Cinnamon–Cinnamaldehyde.

🧠 Memory Trick

Vanilla–Vanillin, Cinnamon–Cinnamaldehyde.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Natural Sources

6 Carbonyl compounds are recognized as constituents of all the following EXCEPT:

A Fabrics

B Flavourings

C Plastics

D Heavy metals

💡 Short Explanation

�� Carbonyl compounds are used in flavourings. �� Used in plastics and fabrics. �� Heavy metals are unrelated.

✅ Correct Answer Explanation

Carbonyl compounds are widely used in flavourings, perfumes, plastics, fabrics, adhesives, paints and pharmaceuticals. They are not constituents of heavy metals.

❓ Why Other Options Are Incorrect

�� Options A, B and C are applications of carbonyl compounds.
�� Option D is unrelated to carbonyl chemistry.

🎯 Strategy

Used

Elimination

Application:

�� Identify the unrelated category.

Final Logic:

�� Heavy metals do not belong to carbonyl compound applications.

🧠 Memory Trick

Carbonyl compounds are organic, not metallic.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Uses of Carbonyl Compounds

7 The common names of most aldehydes reflect the Latin or Greek term for:

A The original source of the acid or aldehyde

B The number of carbon atoms in the chain

C The physical colour of the substance

D The scientist who discovered the structure

💡 Short Explanation

�� Common names are historically derived. �� They often reflect the natural source. �� Latin or Greek origins are frequently used.

✅ Correct Answer Explanation

The common names of aldehydes are generally derived from the common names of the corresponding carboxylic acids, which often originate from Latin or Greek names associated with their natural sources. Examples: Formic acid (from ants) → Formaldehyde Acetic acid (from vinegar) → Acetaldehyde

❓ Why Other Options Are Incorrect

�� Option B → Refers more closely to IUPAC nomenclature.
�� Option C → Colour is not the naming basis.
�� Option D → Aldehydes are not commonly named after scientists.

🎯 Strategy

Used

Historical Naming Recall

Application:

�� Identify the origin of common nomenclature.

Final Logic:

�� Common names often reflect the original source.

🧠 Memory Trick

Common names come from common sources.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Common Nomenclature

8 Alkyl phenyl ketones are usually named by adding the name of the acyl group as a prefix to which word?

A Benzene

B Phenone

C Ketone

D Carbaldehyde

💡 Short Explanation

�� Alkyl phenyl ketones use common nomenclature. �� Acyl group name is used as a prefix. �� The suffix word is "phenone".

✅ Correct Answer Explanation

In common nomenclature, alkyl phenyl ketones are named by writing the acyl group as a prefix followed by the word phenone. Example: C₆H₅COCH₃ → Acetophenone

❓ Why Other Options Are Incorrect

�� Option A → Not the accepted suffix.
�� Option C → Too general.
�� Option D → Used for aldehydes attached to rings.

🎯 Strategy

Used

Naming Recall

Application:

�� Recall common naming of aromatic ketones.

Final Logic:

�� Acyl group + Phenone.

🧠 Memory Trick

Phenyl ketone = Phenone.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Common Names of Ketones

9 Arrange the following Greek letters in correct sequential order representing distance from the carbonyl group (closest to farthest):
(A) γ (gamma)
(B) α (alpha)
(C) δ (delta)
(D) β (beta)

A (B), (D), (A), (C)

B (A), (B), (C), (D)

C (B), (A), (D), (C)

D (D), (C), (B), (A)

💡 Short Explanation

�� α-carbon is nearest to carbonyl group. �� Followed by β, γ and δ. �� Distance increases in that order.

✅ Correct Answer Explanation

In common nomenclature, carbon atoms are designated by Greek letters moving away from the carbonyl carbon: α → β → γ → δ Therefore: (B) α → (D) β → (A) γ → (C) δ

❓ Why Other Options Are Incorrect

�� Options B, C and D do not follow the correct Greek-letter sequence.

🎯 Strategy

Used

Ordering

Application:

�� Recall Greek-letter carbon numbering.

Final Logic:

�� α → β → γ → δ.

🧠 Memory Trick

Alpha Before Gamma and Delta.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Common Nomenclature

10 The common name of CH₃CH(OCH₃)CHO indicates the methoxy group is on the α-carbon. What is this common name?

A 2-Methoxypropanal

B α-Methoxypropionaldehyde

C β-Methoxypropionaldehyde

D Methoxyacetone

💡 Short Explanation

�� Parent aldehyde is propionaldehyde. �� Methoxy group is on the α-carbon. �� Common nomenclature uses Greek letters.

✅ Correct Answer Explanation

The structure CH₃CH(OCH₃)CHO is derived from propionaldehyde (propanal). Since the methoxy substituent is attached to the α-carbon (the carbon adjacent to the aldehyde carbon), the common name becomes: α-Methoxypropionaldehyde

❓ Why Other Options Are Incorrect

�� Option A → IUPAC name, not common name.
�� Option C → Methoxy group is not on the β-carbon.
�� Option D → Represents a ketone-related name.

🎯 Strategy

Used

Common Nomenclature Analysis

Application:

�� Identify parent aldehyde and Greek-letter position.

Final Logic:

�� Methoxy on α-carbon gives α-Methoxypropionaldehyde.

🧠 Memory Trick

Adjacent carbon = α-carbon.

📚 Class XII – Chemistry – Chapter: Aldehydes, Ketones and Carboxylic Acids – Topic: Common Nomenclature of Aldehydes and Ketones

11 Regarding the IUPAC rules governing aliphatic aldehydes and ketones:
1. The longest carbon chain is numbered starting from the carbon of the aldehyde group.
2. In ketones, numbering begins from the end nearer to the carbonyl group.
3. Substituents are prefixed in order of increasing molecular weight.

A 1 and 2

B 2 and 3

C 1 and 3

D 1, 2 and 3

💡 Short Explanation

�� Aldehyde carbon is always carbon-1. �� Ketones are numbered nearest to C=O. �� Substituents are arranged alphabetically, not by molecular weight.

✅ Correct Answer Explanation

In aldehydes, numbering starts from the aldehyde carbon. In ketones, numbering begins from the end nearest to the carbonyl group so that it receives the lowest possible locant. Substituents are listed alphabetically, not according to molecular weight.

❓ Why Other Options Are Incorrect

�� Statement 3 is incorrect.
�� Options B, C and D include statement 3.

🎯 Strategy

Used

Elimination

🧠 Memory Trick

CHO gets carbon-1; C=O gets lowest number.

📚 Aldehydes, Ketones and Carboxylic Acids – IUPAC Nomenclature

12 When applying IUPAC nomenclature for ketones, the substituent positions are indicated by numerals and are listed in:

A Increasing numerical order

B Alphabetical order

C Decreasing molecular mass

D Random sequential order

💡 Short Explanation

�� Substituent names are arranged alphabetically. �� Locants indicate positions. �� Standard IUPAC convention.

✅ Correct Answer Explanation

In IUPAC nomenclature, substituent names are written in alphabetical order while their positions are indicated by appropriate locants.

❓ Why Other Options Are Incorrect

�� Option A → Refers to numbering, not naming order.
�� Option C → Molecular mass is irrelevant.
�� Option D → IUPAC rules are systematic.

🎯 Strategy

Used

Nomenclature Recall

🧠 Memory Trick

Alphabet first, numbering next.

📚 Aldehydes, Ketones and Carboxylic Acids – IUPAC Rules

13 In the IUPAC name 3-Methylcyclohexanecarbaldehyde, the ring carbon attached to the aldehyde group is designated as number:

A 1

B 2

C 3

D 4

💡 Short Explanation

�� Ring numbering starts at the carbon attached to CHO. �� This carbon receives position 1. �� Used in cyclic aldehydes.

✅ Correct Answer Explanation

For cycloalkane carbaldehydes, numbering begins from the ring carbon directly attached to the aldehyde group. Therefore, that carbon is assigned number 1.

❓ Why Other Options Are Incorrect

�� Options B, C and D violate IUPAC numbering rules.

🎯 Strategy

Used

Ring Numbering Analysis

🧠 Memory Trick

CHO-attached ring carbon = C-1.

📚 Aldehydes, Ketones and Carboxylic Acids – Cyclic Aldehydes

14 The correct IUPAC name indicating proper chain numbering for CH₃COCH₂CH₂CH₃ is:

A Pentan-2-one

B Pentan-3-one

C Methyl n-propyl ketone

D Butanone

💡 Short Explanation

�� Five-carbon chain present. �� Carbonyl gets lowest possible number. �� Ketone located at carbon-2.

✅ Correct Answer Explanation

The longest chain contains five carbon atoms. Numbering starts from the end nearest the carbonyl group, placing the ketone at carbon-2. Hence the correct name is pentan-2-one.

❓ Why Other Options Are Incorrect

�� Option B → Incorrect numbering.
�� Option C → Common name, not IUPAC.
�� Option D → Wrong carbon count.

🎯 Strategy

Used

IUPAC Naming

🧠 Memory Trick

Count chain first, then locate C=O.

📚 Aldehydes, Ketones and Carboxylic Acids – Ketone Nomenclature

15 Identify the proper structure prefix location format for a cyclic compound containing a carbonyl group within a 6-carbon ring and a methyl group on the adjacent carbon.

A 2-Methylcyclohexanone

B α-Methylcyclohexanone

C 1-Methylcyclohexan-2-one

D Cyclohexyl methyl ketone

💡 Short Explanation

�� Carbonyl carbon is numbered 1. �� Adjacent carbon becomes carbon-2. �� Methyl group is attached at carbon-2.

✅ Correct Answer Explanation

In cyclohexanone, the carbonyl carbon is assigned position 1. A methyl group attached to the adjacent carbon therefore receives locant 2, giving the name 2-methylcyclohexanone.

❓ Why Other Options Are Incorrect

�� Option B → Common notation, not preferred IUPAC.
�� Option C → Incorrect numbering format.
�� Option D → Different naming system.

🎯 Strategy

Used

Cyclic Ketone Numbering

🧠 Memory Trick

Cyclohexanone starts counting from the carbonyl carbon.

📚 Aldehydes, Ketones and Carboxylic Acids – Nomenclature of Cyclic Ketones

16 When an aldehyde group is attached to a cycloalkane ring, the numbering of the ring carbon atoms starts from:

A The carbon atom attached to the aldehyde group

B The carbon opposite to the aldehyde group

C The carbon with the bulkiest substituent

D Any carbon atom on the ring

💡 Short Explanation

�� Aldehyde group has priority. �� Ring numbering starts from the carbon attached to –CHO. �� This carbon is assigned number 1.

✅ Correct Answer Explanation

When an aldehyde group is directly attached to a cycloalkane ring, the ring carbon bonded to the aldehyde group is assigned number 1. Numbering then continues around the ring to give substituents the lowest possible locants.

❓ Why Other Options Are Incorrect

�� Option B → Numbering does not start from the opposite carbon.
�� Option C → Bulky substituent does not get priority over aldehyde group.
�� Option D → Numbering is not random.

🎯 Strategy

Used

Priority Rule Application

🧠 Memory Trick

Ring carbon attached to CHO = Number 1.

📚 Aldehydes, Ketones and Carboxylic Acids – Cyclic Aldehyde Nomenclature

17 The common name benzaldehyde is universally accepted by IUPAC. What is its systematic IUPAC name prior to this acceptance?

A Phenylmethanal

B Benzenecarbaldehyde

C Benzyl aldehyde

D Phenol

💡 Short Explanation

�� Benzaldehyde has –CHO attached to benzene. �� Systematic name uses carbaldehyde suffix. �� Correct name is benzenecarbaldehyde.

✅ Correct Answer Explanation

For an aldehyde group attached directly to a benzene ring, the systematic IUPAC name is benzenecarbaldehyde. However, the common name benzaldehyde is also accepted by IUPAC.

❓ Why Other Options Are Incorrect

�� Option A → Not the accepted systematic answer here.
�� Option C → Not an IUPAC name.
�� Option D → Different functional group.

🎯 Strategy

Used

Nomenclature Recall

🧠 Memory Trick

Benzene + CHO = Benzenecarbaldehyde.

📚 Aldehydes, Ketones and Carboxylic Acids – Aromatic Aldehyde Nomenclature

18 What is the correct IUPAC name for m-Bromobenzaldehyde?

A 1-Bromobenzaldehyde

B 2-Bromobenzaldehyde

C 3-Bromobenzaldehyde

D 4-Bromobenzaldehyde

💡 Short Explanation

�� Meta position means 1,3-disubstitution. �� Aldehyde carbon is position 1. �� Bromine is at position 3.

✅ Correct Answer Explanation

In benzaldehyde, the carbon attached to the aldehyde group is assigned position 1. A meta substituent is located at position 3 relative to the aldehyde group. Therefore, m-bromobenzaldehyde is named 3-bromobenzaldehyde.

❓ Why Other Options Are Incorrect

�� Option A → Bromine cannot occupy the same carbon as –CHO.
�� Option B → Represents ortho-bromobenzaldehyde.
�� Option D → Represents para-bromobenzaldehyde.

🎯 Strategy

Used

Position Mapping

🧠 Memory Trick

Meta = 1,3.

📚 Aldehydes, Ketones and Carboxylic Acids – Aromatic Aldehyde Nomenclature

19 According to common vs IUPAC nomenclature comparisons, the common name for Prop-2-enal is:

A Acrolein

B Valeraldehyde

C Phthaldehyde

D Acetone

💡 Short Explanation

�� Prop-2-enal is an unsaturated aldehyde. �� Its common name is acrolein. �� It contains three carbons.

✅ Correct Answer Explanation

Prop-2-enal has the structure CH₂=CH–CHO. Its common name is acrolein.

❓ Why Other Options Are Incorrect

�� Option B → Common name of pentanal.
�� Option C → Common name related to benzene dialdehyde.
�� Option D → Common name of propanone.

🎯 Strategy

Used

Naming Recall

🧠 Memory Trick

Prop-2-enal = Acrolein.

📚 Aldehydes, Ketones and Carboxylic Acids – Common Names

20 The functional structural unit of Valeraldehyde corresponds to a straight-chain aliphatic aldehyde. How many carbon atoms does this molecule unit contain?

A 3

B 4

C 5

D 6

💡 Short Explanation

�� Valeraldehyde is pentanal. �� Pentanal contains five carbon atoms. �� It is a straight-chain aldehyde.

✅ Correct Answer Explanation

Valeraldehyde is the common name of pentanal. The prefix "pent-" indicates five carbon atoms in the main chain.

❓ Why Other Options Are Incorrect

�� Option A → Three carbons correspond to propanal.
�� Option B → Four carbons correspond to butanal.
�� Option D → Six carbons correspond to hexanal.

🎯 Strategy

Used

Naming Recall

🧠 Memory Trick

Valeraldehyde = Pentanal = 5 carbons.

📚 Aldehydes, Ketones and Carboxylic Acids – Common and IUPAC Names

CUET UG Chemistry Booster Test – 2 Introduction & Nomenclature (Aldehydes and Ketones)

CUET UG Chemistry Booster Test - 2 Introduction & Nomenclature (Aldehydes and Ketones)

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