Chemistry is a subject that builds the foundation of modern science, and one of its most crucial aspects is the systematic naming of compounds. For Bihar Board Class 12 Chemistry IUPAC Name (BSEB), mastering the IUPAC nomenclature system is essential not only for board exams but also for competitive exams like JEE, NEET, and state-level entrance tests.
The International Union of Pure and Applied Chemistry (IUPAC) developed a universal system of naming chemical compounds to eliminate confusion caused by local or traditional names. This system helps chemists, researchers, and students across the world to identify compounds accurately.
In this comprehensive guide, we will cover every aspect of Bihar Board Class 12 Chemistry IUPAC Name, including its rules, importance, classification, examples, and shortcuts to remember. Whether you are preparing for your board exams or competitive exams, this detailed blog will serve as a complete study resource.
Bihar Board Class 12 Chemistry IUPAC Name – Rules, Examples & Guide 2025
Importance of IUPAC Nomenclature in Class 12
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Universal Language of Chemistry – It allows scientists across the globe to communicate chemical information clearly.
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Exam Relevance – Questions based on writing or identifying IUPAC names frequently appear in Bihar Board Class 12 Chemistry exams.
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Foundation for Higher Studies – A strong grasp of nomenclature helps in Organic, Inorganic, and Physical Chemistry at graduation and competitive levels.
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Conceptual Clarity – It builds logical thinking as the names are structured step by step following a pattern.
General Rules of IUPAC Nomenclature
IUPAC naming has three main parts:
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Prefix: Indicates substituents or side chains.
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Parent Chain: The longest continuous carbon chain.
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Suffix: Indicates the functional group.
Step-by-Step Rules:
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Select the Longest Carbon Chain
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The chain containing the principal functional group must be chosen.
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Number the Chain
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Start numbering from the end nearer to the functional group or substituent.
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Identify and Name Substituents
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Groups attached to the main chain are named as prefixes.
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Assign Locants (Positions)
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Numbers are used to show the position of substituents or double/triple bonds.
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Write the Name in Correct Order
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Prefix + Parent Name + Suffix
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IUPAC Naming of Organic Compounds
Organic compounds form the backbone of Class 12 Chemistry. Let’s explore their nomenclature.
1. Alkanes (Single Bond Compounds)
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General Formula: CnH2n+2
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Suffix: -ane
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Example: CH4 → Methane
Examples for Bihar Board Students:
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CH3–CH3 → Ethane
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CH3–CH2–CH3 → Propane
2. Alkenes (Double Bond Compounds)
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General Formula: CnH2n
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Suffix: -ene
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Rule: Numbering starts from the end nearest to the double bond.
Examples:
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CH2=CH2 → Ethene
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CH3–CH=CH2 → Prop-1-ene
3. Alkynes (Triple Bond Compounds)
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General Formula: CnH2n–2
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Suffix: -yne
Examples:
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CH≡CH → Ethyne
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CH3–C≡CH → Prop-1-yne
4. Haloalkanes (Halogen Compounds)
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Prefix: fluoro, chloro, bromo, iodo
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Example: CH3Cl → Chloromethane
5. Alcohols (–OH group)
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Suffix: -ol
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Example: CH3–OH → Methanol
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Example: CH3–CH2–OH → Ethanol
6. Aldehydes (–CHO group)
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Suffix: -al
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Example: H–CHO → Methanal (formaldehyde)
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Example: CH3–CHO → Ethanal
7. Ketones (–CO– group)
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Suffix: -one
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Example: CH3–CO–CH3 → Propanone (acetone)
8. Carboxylic Acids (–COOH group)
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Suffix: -oic acid
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Example: H–COOH → Methanoic acid
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Example: CH3–COOH → Ethanoic acid (acetic acid)
9. Amines (–NH2 group)
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Suffix: -amine
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Example: CH3–NH2 → Methanamine
10. Aromatic Compounds
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Parent compound: Benzene
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Substituents are named as prefixes.
Examples:
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C6H6 → Benzene
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C6H5–Cl → Chlorobenzene
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C6H5–NO2 → Nitrobenzene
IUPAC Naming of Inorganic Compounds
Inorganic chemistry also requires systematic naming.
1. Binary Ionic Compounds
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Metal + Non-metal (ending with –ide)
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Example: NaCl → Sodium chloride
2. Oxides
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Example: CO2 → Carbon dioxide
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Example: SO2 → Sulphur dioxide
3. Acids
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HCl → Hydrochloric acid
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H2SO4 → Sulphuric acid
4. Salts
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Na2SO4 → Sodium sulphate
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KNO3 → Potassium nitrate
Table: Root Names for Carbon Atoms in IUPAC
| No. of Carbons | Root Name | Example Compound |
|---|---|---|
| 1 | Meth | Methane |
| 2 | Eth | Ethane |
| 3 | Prop | Propane |
| 4 | But | Butane |
| 5 | Pent | Pentane |
| 6 | Hex | Hexane |
| 7 | Hept | Heptane |
| 8 | Oct | Octane |
| 9 | Non | Nonane |
| 10 | Dec | Decane |
Tricks to Remember IUPAC Names
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Mnemonic for Carbon Roots – My Elephant Plays Ball Perfectly Having High Order Neat Dance.
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Always give priority to functional groups while numbering.
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Use lowest locant rule – assign minimum numbers to double bonds or functional groups.
Previous Year Bihar Board Questions (Examples)
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Write the IUPAC name of CH3–CH2–OH.
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Answer: Ethanol
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Write the IUPAC name of CH3–COOH.
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Answer: Ethanoic acid
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Write the IUPAC name of C6H5–NO2.
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Answer: Nitrobenzene
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FAQs on Bihar Board Class 12 Chemistry IUPAC Name
Q1. What is IUPAC nomenclature in Chemistry?
IUPAC nomenclature is the international system of naming chemical compounds scientifically.
Q2. Why is IUPAC important for Class 12 Bihar Board students?
Because several questions are asked directly from nomenclature in board exams and it builds a foundation for higher studies.
Q3. How many types of IUPAC naming systems are there?
Mainly two – Organic compound nomenclature and Inorganic compound nomenclature.
Q4. Which chapters of Bihar Board Chemistry include IUPAC names?
Organic Chemistry chapters such as Haloalkanes, Alcohols, Aldehydes, Carboxylic acids, Amines, and Aromatics.
Q5. Can traditional names still be used?
Yes, but IUPAC names are preferred in exams and scientific writing.
Q6. What is the IUPAC name of acetone?
The IUPAC name of acetone is Propanone.
Q7. How to identify the parent chain in IUPAC naming?
Always select the longest continuous chain containing the functional group.
Q8. What is the IUPAC name of CH3–CH=CH2?
It is Prop-1-ene.
Q9. Are IUPAC questions scoring in Bihar Board exams?
Yes, they are direct and easy-to-score questions if you follow the rules.
Q10. Where can I practice Bihar Board Chemistry IUPAC questions?
From NCERT textbooks, Bihar Board prescribed books, and previous year exam papers.
Previous Year Objective Questions on Bihar Board Class 12 Chemistry IUPAC Name
Q1. The IUPAC name of CH3–CH2–OH is:
a) Methanol
b) Ethanol
c) Propanol
d) Ethanal
Answer: ethanol
Q2. The IUPAC name of CH3–COOH is:
a) Formic acid
b) Methanoic acid
c) Acetic acid
d) Ethanoic acid
Answer : ethanoic acid
Q3. The IUPAC name of CH3–CH=CH2 is:
a) Prop-1-ene
b) Prop-2-ene
c) Propane
d) Ethene
Answer : Prop-1-ene
Q4. The IUPAC name of C6H5–Cl is:
a) Chloromethane
b) Benzyl chloride
c) Chlorobenzene
d) Benzyl alcohol
Answer: chlorobenzene
Q5. The IUPAC name of CH3–CO–CH3 is:
a) Acetone
b) Propanone
c) Ethanal
d) Methanal
Answer: propanone
Q6. The IUPAC name of HCHO is:
a) Methanol
b) Methanal
c) Formaldehyde
d) Ethanal
Answer: methanal
Q7. The IUPAC name of CH≡CH is:
a) Ethane
b) Ethyne
c) Propene
d) Ethene
Answer: ethyne
Q8. The IUPAC name of CH3–CH2–NH2 is:
a) Methylamine
b) Ethanamine
c) Ethylamine
d) Aminoethane
Answer : Ethanamine
Q9. The IUPAC name of CH3–O–CH3 is:
a) Dimethyl ether
b) Methoxyethane
c) Ethoxyethane
d) Ethanol
Answer: Dimethyl ether
Q10. The IUPAC name of CH3–CH2–CHO is:
a) Methanal
b) Ethanal
c) Propanal
d) Propanone
Answer: Propanal
Q11. The IUPAC name of C6H6 is:
a) Cyclohexane
b) Benzene
c) Phenol
d) Hexene
Answer : benzene
Q12. The IUPAC name of CH3–CH(OH)–CH3 is:
a) Propan-2-ol
b) Propan-1-ol
c) Ethanol
d) Butanol
Answer: Propan-2-ol
Q13. The IUPAC name of CH3–CH2–COOH is:
a) Methanoic acid
b) Ethanoic acid
c) Propanoic acid
d) Butanoic acid
Answer :Propanoic acid
Q14. The IUPAC name of CH3–CO–CH2–CH3 is:
a) Butanal
b) Butanone
c) Butanol
d) Butanoic acid
Answer: Butanone
Q15. The IUPAC name of CH2=CH–Cl is:
a) Chloroethane
b) Chloroethene
c) Vinyl chloride
d) Ethyl chloride
Answer: Chloroethene
Conclusion
Understanding and practicing the Bihar Board Class 12 Chemistry IUPAC Name system is a must for every student aiming for excellent exam results. Once you master the rules, naming compounds becomes simple and logical. Remember, IUPAC nomenclature is not just for board exams but also a foundation for your higher studies in Chemistry, Pharmacy, Medicine, and Engineering.
Bihar Board Class 12 Chemistry IUPAC Name