संक्षेप में: RBSE Class 12 Chemistry में reactions से 25-30 marks directly आते हैं — Organic Named Reactions, Conversion Reactions, और Chemical Equations मिलाकर। इस guide में 30 most important Named Reactions (Sandmeyer, Friedel-Crafts, Aldol, Cannizzaro, Wurtz, etc.), Chapter-wise reaction tables, Conversion pathways, diagram-type questions, previous year analysis, और exam-day writing format Hindi में दिए गए हैं। RBSE 2027 exam Feb-Mar expected।
Chemistry Exam Structure — RBSE Class 12
| Component | Marks | Details |
|---|---|---|
| Theory Paper | 56 | Exam hall में लिखना |
| Practical Exam | 24 | Lab experiments + viva |
| कुल | 80 | — |
Note: RBSE Class 12 Chemistry = 56 marks theory + 24 marks practical (total 80, not 100)
Marks Distribution — Unit-wise
| Unit | Topic | Marks | Reactions Count |
|---|---|---|---|
| ठोस अवस्था + विलयन (Solid State + Solutions) | Physical Chemistry | 8 | Low |
| विद्युत रसायन + रासायनिक बल गतिकी (Electrochemistry + Kinetics) | Physical Chemistry | 8 | Medium |
| पृष्ठ रसायन + p-Block + d-Block (Surface + p/d Block) | Inorganic | 12 | Medium |
| हैलोऐल्केन + ऐल्कोहॉल + फ़ीनॉल (Haloalkanes + Alcohols) | Organic | 12 | ★★★ Very High |
| ऐल्डिहाइड + कार्बोक्सिलिक + एमीन (Aldehyde + Acid + Amine) | Organic | 10 | ★★★ Very High |
| जैव अणु + बहुलक + दैनिक रसायन (Biomolecules + Polymers) | Applied | 6 | Low |
30 Most Important Named Reactions
Haloalkanes & Haloarenes (Chapter 10)
| # | Reaction | क्या होता है | Example |
|---|---|---|---|
| 1 | Sandmeyer Reaction | Diazonium salt → Aryl halide (CuCl/CuBr) | C₆H₅N₂⁺Cl⁻ + CuCl → C₆H₅Cl + N₂ |
| 2 | Wurtz Reaction | 2 Alkyl halides + Na → Alkane | 2CH₃Br + 2Na → C₂H₆ + 2NaBr |
| 3 | Wurtz-Fittig Reaction | Aryl halide + Alkyl halide + Na → Toluene type | C₆H₅Br + CH₃Br + 2Na → C₆H₅CH₃ |
| 4 | Finkelstein Reaction | Alkyl halide + NaI → Alkyl iodide | R-Cl + NaI → R-I + NaCl |
| 5 | Swarts Reaction | Alkyl halide + AgF/Hg₂F₂ → Fluoro compound | CH₃Br + AgF → CH₃F + AgBr |
Alcohols, Phenols & Ethers (Chapter 11)
| # | Reaction | क्या होता है |
|---|---|---|
| 6 | Williamson Synthesis | Sodium alkoxide + Alkyl halide → Ether |
| 7 | Kolbe's Reaction | Phenol + NaOH + CO₂ → Salicylic acid |
| 8 | Reimer-Tiemann Reaction | Phenol + CHCl₃ + NaOH → Salicylaldehyde |
Aldehydes, Ketones & Carboxylic Acids (Chapter 12)
| # | Reaction | क्या होता है | Board Exam Frequency |
|---|---|---|---|
| 9 | Aldol Condensation | 2 Aldehydes (with α-H) → β-hydroxy aldehyde | ★★★ बहुत important |
| 10 | Cannizzaro Reaction | Aldehyde (no α-H) + NaOH → Alcohol + Salt | ★★★ हर साल आता है |
| 11 | Clemmensen Reduction | Carbonyl → CH₂ (Zn-Hg/HCl) | ★★★ |
| 12 | Wolff-Kishner Reduction | Carbonyl → CH₂ (NH₂NH₂/KOH) | ★★★ |
| 13 | Tollens' Test | Aldehyde + [Ag(NH₃)₂]⁺ → Silver mirror | ★★ (practical + theory) |
| 14 | Fehling's Test | Aldehyde + Cu²⁺ → Red ppt (Cu₂O) | ★★ |
| 15 | Rosenmund Reduction | Acyl chloride + H₂/Pd-BaSO₄ → Aldehyde | ★★ |
| 16 | Stephen Reduction | Nitrile + SnCl₂/HCl → Aldehyde | ★★ |
| 17 | Hell-Volhard-Zelinsky (HVZ) | Carboxylic acid + Br₂/P → α-bromo acid | ★★ |
| 18 | Etard Reaction | Toluene + CrO₂Cl₂ → Benzaldehyde | ★ |
Amines (Chapter 13)
| # | Reaction | क्या होता है |
|---|---|---|
| 19 | Gabriel Phthalimide | Potassium phthalimide + R-X → Primary amine |
| 20 | Hoffmann Bromamide | Amide + Br₂ + NaOH → Primary amine (-1 carbon) |
| 21 | Carbylamine (Isocyanide) Test | Primary amine + CHCl₃ + KOH → बदबूदार isocyanide |
| 22 | Diazotisation | Aromatic amine + NaNO₂ + HCl → Diazonium salt |
| 23 | Coupling Reaction | Diazonium salt + Phenol/Amine → Azo compound (dye) |
| 24 | Hinsberg Test | Amine classification using C₆H₅SO₂Cl |
Other Important Reactions
| # | Reaction | Chapter | Importance |
|---|---|---|---|
| 25 | Friedel-Crafts Alkylation | Hydrocarbons | Benzene + R-X → Alkylbenzene |
| 26 | Friedel-Crafts Acylation | Hydrocarbons | Benzene + RCOCl → Ketone |
| 27 | Gattermann Reaction | Haloarenes | Similar to Sandmeyer (Cu powder) |
| 28 | Balz-Schiemann Reaction | Haloarenes | Diazonium + HBF₄ → Aryl fluoride |
| 29 | Cross Aldol | Aldehydes | Two different aldehydes → mixed product |
| 30 | Kolbe Electrolysis | Carboxylic Acids | Electrolysis → Alkane |
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Important Conversion Pathways
Organic Conversions (5-6 marks questions)
| From → To | Key Steps | Marks |
|---|---|---|
| Ethanol → Ethanal | Oxidation (K₂Cr₂O₇/H⁺) | 2-3 |
| Benzene → Aniline | Nitration → Reduction (Sn/HCl) | 3-4 |
| Aniline → p-Bromoanile | Diazotisation → Sandmeyer | 3-4 |
| Phenol → Aspirin | Acetylation (CH₃COCl) | 2-3 |
| Methane → Ethane | Wurtz reaction (CH₃Br + Na) | 2 |
| Acetaldehyde → Acetic acid | Oxidation (K₂Cr₂O₇/H⁺) | 2 |
| Benzaldehyde → Cinnamic acid | Perkin reaction (Ac₂O) | 3 |
| Nitrobenzene → Azobenzene | Reduction + Diazotisation + Coupling | 4-5 |
Inorganic Reactions — Must Remember
p-Block Elements (Chapter 7)
| Reaction | Equation |
|---|---|
| Ozone layer depletion | CFCl₃ → CF₂Cl + Cl· (UV light) |
| Ammonia preparation | NH₄Cl + Ca(OH)₂ → NH₃ + CaCl₂ + H₂O |
| Nitric acid manufacturing | 4NH₃ + 5O₂ → 4NO + 6H₂O (Ostwald process) |
| Sulphuric acid | Contact process: 2SO₂ + O₂ → 2SO₃ (V₂O₅) |
d-Block Elements (Chapter 8)
| Reaction | Use |
|---|---|
| KMnO₄ as oxidising agent | MnO₄⁻ → Mn²⁺ (acidic medium) |
| K₂Cr₂O₇ as oxidising agent | Cr₂O₇²⁻ → 2Cr³⁺ (acidic medium) |
| Complex formation | [Fe(CN)₆]⁴⁻, [Cu(NH₃)₄]²⁺ |
Answer Writing Format — Reactions के लिए
Named Reaction लिखने का सही तरीका (Full marks)
- Reaction Name लिखो (bold/underline)
- General Equation लिखो (with reagents and conditions)
- Example दो (specific compound)
- Conditions mention करो (temperature, catalyst, medium)
Example: Aldol Condensation
Aldol Condensation:
When two molecules of aldehyde or ketone having
α-hydrogen react in the presence of dilute NaOH,
β-hydroxy aldehyde (aldol) is formed.
CH₃CHO + CH₃CHO → CH₃CH(OH)CH₂CHO
(β-hydroxy butanal / Aldol)
Dilute NaOH
(base catalyst)
Common Answer Writing Mistakes
| गलती | सही तरीका |
|---|---|
| Equation balance नहीं की | हमेशा balanced equation लिखो |
| Catalyst/condition skip | Reagent, temperature, catalyst mention करो |
| Arrow direction गलत | Products → side में |
| Named reaction का name skip | Name + reaction दोनों लिखो |
| Only equation, no explanation | 1-2 line explanation ज़रूर लिखो |
Previous Year Pattern — क्या Repeat होता है
Most Repeated Question Types (2022-2026)
| Question Type | Marks | Frequency |
|---|---|---|
| Named reaction + example | 2-3 | हर साल |
| Conversion (A → B → C) | 3-5 | हर साल |
| Distinguish between reactions (Tollens, Fehling) | 2-3 | 80% years |
| Mechanism of reaction | 3-4 | 50% years |
| Chemical equation complete करो | 1-2 | MCQ section |
| Name the reagent | 1 | MCQ section |
Quick Revision — Exam से 1 रात पहले
Top 15 Reactions (ये confirm आएंगे)
- Aldol Condensation
- Cannizzaro Reaction
- Sandmeyer Reaction
- Wurtz Reaction
- Friedel-Crafts (Alkylation + Acylation)
- Williamson Synthesis
- Kolbe's Reaction
- Reimer-Tiemann
- Gabriel Phthalimide
- Hoffmann Bromamide
- Clemmensen Reduction
- Wolff-Kishner Reduction
- Diazotisation
- Coupling Reaction
- HVZ Reaction
Reaction Memory Tricks
- Aldol vs Cannizzaro: α-hydrogen है = Aldol, नहीं है = Cannizzaro
- Clemmensen vs Wolff-Kishner: Acidic condition = Clemmensen (Zn-Hg), Basic = Wolff-Kishner (NH₂NH₂)
- Sandmeyer vs Gattermann: CuX salt = Sandmeyer, Cu powder = Gattermann
- Tollens vs Fehling: Silver mirror = Tollens, Red ppt = Fehling
Frequently Asked Questions
Chemistry board exam में reactions से कितने marks आते हैं?
Direct reactions से 25-30 marks (56 में से 45-55%) आते हैं। Named reactions 8-10 marks, Conversion reactions 5-6 marks, Chemical equations 5-8 marks, और reaction-based MCQ 5-6 marks। Reactions master करो तो half paper confident है।
30 reactions कैसे याद रखें?
Chapter-wise groups बनाओ: Haloalkanes (5 reactions), Alcohols (3), Aldehydes (10), Amines (6), Others (6)। Daily 5 reactions revise करो — 6 days cycle। Flashcards बनाओ — एक side reaction name, दूसरी side equation। रोज़ सोने से पहले 10 min flashcard practice।
Organic Chemistry कमज़ोर है — reactions समझ नहीं आती?
Mechanism समझो, रटो मत। हर reaction में 3 steps: reagent attack → bond break → new bond form। NCERT textbook की reactions ध्यान से पढ़ो — mechanism section skip मत करो। Padhaao AI tutor से step-by-step mechanism practice करो। 2-3 हफ्ते consistent practice से organic reactions comfortable हो जाएंगी।
Practical exam में कौन-सी reactions आती हैं?
Salt analysis (cation + anion identification), acid-base titration, और organic compound identification। Practical में भी reactions knowledge important है — viva में named reactions पूछे जाते हैं। Practical = 24 marks, ये आसान marks हैं अगर lab में regular practice की हो।
Padhaao AI tutor से Chemistry reactions step-by-step practice करो — mechanism diagrams, conversion paths, और instant doubt solving। Free = 3 chapters/day।
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