Organic Chemistry deals with the structure, properties, reactions, and synthesis of carbon-containing compounds , forming a core part of school-level chemistry, undergraduate curricula, and competitive examinations . This category is designed for Class 11–12 students, undergraduate learners, and competitive exam aspirants , with strong emphasis on conceptual clarity, reaction mechanisms, and application-based learning .
In this section, you will study:
Basic principles of organic chemistry – hybridization, bonding, and structure
Classification and nomenclature of organic compounds
Isomerism – structural and stereoisomerism
Reaction mechanisms – substitution, addition, elimination, and rearrangement
Hydrocarbons – alkanes, alkenes, alkynes, and aromatic compounds
Functional groups and their chemistry – alcohols, aldehydes, ketones, acids, amines, etc.
Named reactions and reagents essential for exams
Biomolecules and polymers (introductory to UG level)
Spectroscopic methods for structure determination (introductory)
NCERT- and UG-aligned explanations , supported by reaction schemes, mechanisms, examples, MCQs, and PYQs
The content is structured to build step-by-step understanding , enhance mechanistic thinking , and help students predict reaction outcomes and solve complex problems .
Master Organic Chemistry to develop strong analytical and reasoning skills , essential for school exams, undergraduate studies, and competitive examinations .
Q. According to Werner's theory, what is the coordination number of a complex with six ligands?
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Solution
The coordination number is defined as the number of ligands surrounding the central metal atom. In this case, it is 6.
Correct Answer:
C
— 6
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Q. According to Werner's theory, what type of isomerism is primarily observed in coordination compounds?
A.
Geometric isomerism
B.
Optical isomerism
C.
Structural isomerism
D.
All of the above
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Solution
Werner's theory accounts for various types of isomerism, including geometric, optical, and structural isomerism in coordination compounds.
Correct Answer:
D
— All of the above
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Q. At which conditions do real gases behave most like ideal gases?
A.
High pressure and low temperature
B.
Low pressure and high temperature
C.
High pressure and high temperature
D.
Low pressure and low temperature
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Solution
Real gases behave most like ideal gases at low pressure and high temperature, where intermolecular forces are minimized.
Correct Answer:
B
— Low pressure and high temperature
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Q. How many stereoisomers can 2,3-dimethylbutane have?
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Solution
2,3-dimethylbutane has no chiral centers, so it has only 1 stereoisomer.
Correct Answer:
A
— 2
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Q. How many stereoisomers can 2-pentene have?
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Solution
2-pentene has two geometric isomers: cis-2-pentene and trans-2-pentene.
Correct Answer:
C
— 2
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Q. How many stereoisomers does 1,2-dichloropropane have?
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Solution
1,2-dichloropropane has one chiral center, leading to 2 stereoisomers.
Correct Answer:
B
— 2
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Q. If 1 mole of NaCl is dissolved in water, how many particles are present in solution?
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Solution
1 mole of NaCl dissociates into 2 particles (1 Na⁺ and 1 Cl⁻), so there are 2 particles in solution.
Correct Answer:
B
— 2
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Q. In a coordination compound, what does the term 'coordination number' refer to?
A.
The number of ligands attached to the metal ion
B.
The total number of electrons in the complex
C.
The oxidation state of the metal ion
D.
The number of unpaired electrons in the metal
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Solution
The coordination number refers to the number of ligands that are directly bonded to the central metal ion in a coordination complex.
Correct Answer:
A
— The number of ligands attached to the metal ion
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Q. In a galvanic cell, which electrode is the site of reduction?
A.
Anode
B.
Cathode
C.
Salt bridge
D.
Electrolyte
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Solution
In a galvanic cell, reduction occurs at the cathode, where electrons are gained.
Correct Answer:
B
— Cathode
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Q. In a nucleophilic substitution reaction, what is the role of the nucleophile?
A.
To donate a proton
B.
To accept electrons
C.
To attack the electrophile
D.
To stabilize the leaving group
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Solution
The nucleophile attacks the electrophile, which is typically a carbon atom bonded to a leaving group, facilitating the substitution.
Correct Answer:
C
— To attack the electrophile
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Q. In a nucleophilic substitution reaction, what is the role of the solvent?
A.
To stabilize the nucleophile
B.
To stabilize the leaving group
C.
To provide a medium for the reaction
D.
To increase the reaction rate
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Solution
The solvent can influence the reaction rate by stabilizing the transition state and the reactants involved in the nucleophilic substitution.
Correct Answer:
D
— To increase the reaction rate
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Q. In a reaction mechanism, what is the term for a species that is formed in one step and consumed in a subsequent step?
A.
Intermediate
B.
Catalyst
C.
Transition state
D.
Reactant
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Solution
An intermediate is a species that is produced in one step of a reaction mechanism and consumed in a later step.
Correct Answer:
A
— Intermediate
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Q. In an addition reaction involving alkenes, what is the product when HBr is added to propene?
A.
1-bromopropane
B.
2-bromopropane
C.
Propyl bromide
D.
Bromopropane
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Solution
The addition of HBr to propene follows Markovnikov's rule, leading to the formation of 1-bromopropane.
Correct Answer:
B
— 2-bromopropane
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Q. In an addition reaction of HBr to an alkene, what is the major product when the alkene is asymmetric?
A.
The product with the bromine on the more substituted carbon.
B.
The product with the bromine on the less substituted carbon.
C.
A racemic mixture of products.
D.
No reaction occurs.
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Solution
According to Markovnikov's rule, in the addition of HBr to an asymmetric alkene, the hydrogen will add to the less substituted carbon, and the bromine will add to the more substituted carbon.
Correct Answer:
A
— The product with the bromine on the more substituted carbon.
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Q. In an E2 elimination reaction, what is the role of the base?
A.
To donate a proton
B.
To stabilize the carbocation
C.
To act as a leaving group
D.
To form a cyclic intermediate
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Solution
In an E2 reaction, the base abstracts a proton from the β-carbon, facilitating the elimination of the leaving group and formation of a double bond.
Correct Answer:
A
— To donate a proton
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Q. In an E2 elimination reaction, which of the following is a requirement for the reaction to occur?
A.
A strong nucleophile
B.
A good leaving group
C.
A polar protic solvent
D.
A tertiary substrate
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Solution
E2 reactions require a good leaving group to facilitate the elimination of the leaving group and the formation of a double bond.
Correct Answer:
B
— A good leaving group
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Q. In an electrophilic addition reaction of HBr to propene, what is the major product formed?
A.
1-bromopropane
B.
2-bromopropane
C.
Propyl bromide
D.
Bromopropane
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Solution
The major product is 2-bromopropane due to Markovnikov's rule, where the bromine adds to the more substituted carbon.
Correct Answer:
B
— 2-bromopropane
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Q. In an SN1 reaction, which step is rate-determining?
A.
Formation of the carbocation
B.
Nucleophilic attack
C.
Deprotonation
D.
Rearrangement
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Solution
The formation of the carbocation is the rate-determining step in an SN1 reaction, as it involves breaking the bond to the leaving group.
Correct Answer:
A
— Formation of the carbocation
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Q. In an SN2 reaction, what is the stereochemical outcome when the nucleophile attacks a chiral center?
A.
Retention of configuration
B.
Inversion of configuration
C.
No change in configuration
D.
Formation of a racemic mixture
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Solution
In an SN2 reaction, the nucleophile attacks from the opposite side of the leaving group, resulting in inversion of configuration.
Correct Answer:
B
— Inversion of configuration
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Q. In an SN2 reaction, which of the following substrates would react the fastest with a nucleophile?
A.
tert-butyl chloride
B.
isopropyl bromide
C.
ethyl chloride
D.
methyl iodide
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Solution
Methyl iodide reacts the fastest in an SN2 reaction due to minimal steric hindrance and the good leaving ability of iodide.
Correct Answer:
D
— methyl iodide
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Q. In an S_N2 reaction, what is the stereochemical outcome when the substrate is a chiral center?
A.
Retention of configuration
B.
Inversion of configuration
C.
Racemization
D.
No stereochemical change
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Solution
S_N2 reactions result in inversion of configuration at the chiral center due to the backside attack of the nucleophile.
Correct Answer:
B
— Inversion of configuration
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Q. In the context of chemical kinetics, what does the term 'activation energy' refer to?
A.
The energy required to break bonds
B.
The energy required to form products
C.
The minimum energy required for a reaction to occur
D.
The energy released during a reaction
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Solution
Activation energy is the minimum energy that reactants must possess for a reaction to occur.
Correct Answer:
C
— The minimum energy required for a reaction to occur
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Q. In the context of reaction mechanisms, what does the term 'rate-determining step' refer to?
A.
The fastest step in a reaction
B.
The step with the highest energy barrier
C.
The step that produces the final product
D.
The step that involves the most reactants
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Solution
The rate-determining step is the slowest step in a reaction mechanism, which controls the overall reaction rate.
Correct Answer:
B
— The step with the highest energy barrier
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Q. In the Friedel-Crafts alkylation of benzene, which of the following is a potential problem?
A.
Polyalkylation
B.
Dealkylation
C.
Hydrogenation
D.
Oxidation
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Solution
Polyalkylation can occur in Friedel-Crafts alkylation, leading to multiple alkyl groups being added to the benzene ring.
Correct Answer:
A
— Polyalkylation
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Q. In the Langmuir adsorption isotherm, what does the term 'K' represent?
A.
Adsorption capacity
B.
Rate constant
C.
Equilibrium constant
D.
Surface area
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Solution
In the Langmuir isotherm, 'K' is the equilibrium constant that relates the concentration of adsorbate in the gas phase to the amount adsorbed on the surface.
Correct Answer:
C
— Equilibrium constant
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Q. In the Langmuir adsorption isotherm, what does the term 'monolayer coverage' refer to?
A.
Complete saturation of the surface
B.
Partial coverage of the surface
C.
Formation of multilayers
D.
No adsorption
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Solution
Monolayer coverage in the Langmuir isotherm indicates that all available adsorption sites on the surface are occupied by adsorbate molecules.
Correct Answer:
A
— Complete saturation of the surface
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Q. In the mechanism of the SN2 reaction, which of the following statements is true?
A.
The reaction involves a carbocation intermediate.
B.
The nucleophile attacks from the opposite side of the leaving group.
C.
The reaction rate depends only on the concentration of the nucleophile.
D.
The reaction occurs in a single step with a trigonal planar transition state.
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Solution
In an SN2 reaction, the nucleophile attacks the substrate from the side opposite to the leaving group, leading to a backside attack.
Correct Answer:
B
— The nucleophile attacks from the opposite side of the leaving group.
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Q. In the nitration of benzene, what is the role of sulfuric acid?
A.
Nucleophile
B.
Electrophile
C.
Catalyst
D.
Solvent
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Solution
Sulfuric acid acts as a catalyst in the generation of the nitronium ion (NO2+), the active electrophile in the nitration reaction.
Correct Answer:
C
— Catalyst
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Q. In the nitration of benzene, which reagent is used to generate the electrophile?
A.
HNO3
B.
H2SO4
C.
NO2+
D.
HCl
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Solution
The electrophile in the nitration of benzene is the nitronium ion (NO2+), generated from the reaction of nitric acid (HNO3) and sulfuric acid (H2SO4).
Correct Answer:
C
— NO2+
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Q. In the nitration of benzene, which reagent is used to generate the nitronium ion?
A.
HNO3
B.
H2SO4
C.
HCl
D.
NaNO2
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Solution
In the nitration of benzene, concentrated sulfuric acid (H2SO4) is used to generate the nitronium ion (NO2+) from nitric acid (HNO3).
Correct Answer:
B
— H2SO4
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