CHE-05 Organic Chemistry: key facts
- Course: CHE-05 Organic Chemistry, IGNOU School of Sciences
- Programme: Bachelor of Science (B.Sc.) under BDP, chemistry elective
- Syllabus: 4 blocks, 20 units
- Term-end exam: 50 marks, 2 hours, 4 compulsory questions
- Paper split: 5 × 1 + 5 × 2 + 5 × 3 + 5 × 4 = 50 marks
- This guess paper: 13 solved questions in a 16-page PDF
- Shown on this page: 5 sample answers; the other 8 are in the paid file
- Papers analysed: 6 sessions, June 2023 to December 2025
CHE 05 Solved Guess Paper is a 16-page PDF of 13 fully answered questions for IGNOU's CHE-05 Organic Chemistry, written for the December 2026 term-end examination. We read six IGNOU sessions from June 2023 to December 2025, marked every topic that returned, and then wrote each answer the way a CHE-05 examiner marks it: reaction first, reagent and condition next, a clean example, and a one-line conclusion.
CHE-05 Organic Chemistry is a course of the IGNOU Bachelor of Science under the Bachelor's Degree Programme (BDP), offered by the School of Sciences as a chemistry elective. It runs across 4 blocks and 20 units, from bonding and stereochemistry to amines, diazonium salts and natural products. Most students do not fail it on theory. They lose marks because a reaction is half-written or a condition like 0 to 5 °C is missing.
1. What the CHE 05 Organic Chemistry Guess Paper Gives You
You get 13 solved long-answer questions covering Blocks 2, 3 and 4 of CHE-05, each tagged with its unit, the sessions it appeared in, its mark value and a target word count. That tag line alone saves time. When a question says Block 4, Unit 19, you know the answer depends on diazotisation and Sandmeyer chemistry, and you know it is worth 4 marks.
The answers are not copied chapter text. Each one opens with a definition, writes the balanced reaction with reagents above the arrow, gives one textbook example such as ethanal for aldol or glucose for mutarotation, and closes with a one-line result. That is the order CHE-05 examiners follow when they mark, so it is the order we followed when we wrote.
Think of this IGNOU CHE 05 Guess Paper as the revision layer on top of your textbook, not a replacement for it. If you still need the unit books, start with the CHE 05 Study Material and then use these answers to see how a full-marks reply is actually shaped in a real exam hall.
2. 5 Sample Answers from the CHE 05 Solved Guess Paper
Below are 5 of the 13 answers, exactly as students receive them in style and depth, one from Block 2, two from Block 3 and two from Block 4. Read them the way an examiner would. Check whether the reaction is complete, whether the condition is stated, and whether the answer stops at the right length for its marks.
Hückel's rule and the structural features of aromaticity
Question: State Hückel's rule. What structural features make a molecule aromatic?
Hückel's rule: a cyclic, planar and fully conjugated molecule is aromatic if it holds (4n + 2) π electrons, where n = 0, 1, 2, 3 and so on. Such molecules gain extra stability because their π electrons are delocalised over the whole ring.
Features needed for aromaticity: (1) a closed ring, so π electrons can circulate; (2) planarity, so p-orbitals overlap properly; (3) complete conjugation, meaning every ring atom carries a p-orbital; (4) a total of 2, 6, 10, 14 and so on π electrons.
Examples: benzene (C6H6) has 6 π electrons, and 6 = 4(1) + 2, so it is aromatic. Naphthalene (C10H8) has 10 π electrons, and 10 = 4(2) + 2. Pyridine (C5H5N) is a planar six-membered ring with 6 π electrons and is also aromatic.
Conclusion: a molecule is aromatic when it is cyclic, planar, fully conjugated and carries (4n + 2) π electrons, which is why benzene, naphthalene and pyridine are unusually stable.
Grignard reagent: preparation, dry conditions and uses
Question: How is a Grignard reagent prepared? Why are dry conditions essential? Describe its use in preparing alkanes and alcohols.
Preparation: a Grignard reagent is an organomagnesium compound, RMgX, where R is an alkyl or aryl group and X is Cl, Br or I. It is made by reacting an alkyl or aryl halide with magnesium metal in dry ether: R–X + Mg → R–MgX (dry ether). Example: C2H5Br + Mg → C2H5MgBr (ethylmagnesium bromide).
Why dry conditions: the reagent is destroyed at once by water, alcohols or any compound with active hydrogen: RMgX + H2O → RH + Mg(OH)X. So it must be prepared and used under strictly anhydrous conditions, usually in dry ether.
Alkanes: hydrolysis gives an alkane, for example CH3MgBr + H2O → CH4 + Mg(OH)Br, so methane is obtained from methylmagnesium bromide.
Alcohols: addition to a carbonyl compound followed by hydrolysis gives an alcohol. With formaldehyde, RMgX + HCHO → RCH2OMgX, which hydrolyses to RCH2OH, a primary alcohol. Other aldehydes (R′CHO) give secondary alcohols, and ketones (R′COR″) give tertiary alcohols.
Conclusion: RMgX is made from a halide and magnesium in dry ether, must be kept away from moisture, and is a key reagent for making alkanes and primary, secondary or tertiary alcohols.
Haloform reaction and the iodoform test
Question: What is the haloform reaction? Which compounds give a positive iodoform test, and how is the test carried out?
Haloform reaction: a methyl ketone, or any compound with the –COCH3 group, reacts with a halogen in alkali to give a haloform. With iodine the product is iodoform (CHI3), a yellow crystalline solid with an antiseptic smell: RCOCH3 + 3I2 + 4NaOH → RCOONa + CHI3 + 3NaI + 3H2O.
Positive compounds: methyl ketones such as acetone (CH3COCH3); secondary alcohols with –CH(OH)CH3 such as isopropyl alcohol; ethanal, the only aldehyde that gives the test; and ethanol, which is first oxidised to ethanal under the test conditions.
Procedure: take a little of the compound in a test tube, add iodine solution and then sodium hydroxide solution, warm gently, and watch for a yellow precipitate. A yellow precipitate of CHI3 with its typical smell confirms a positive test.
Conclusion: the iodoform test picks out the –COCH3 and –CH(OH)CH3 groups, and is the quickest way to separate ethanol and ethanal from methanol and other aldehydes.
Diazotisation and diazonium salt conversions
Question: What is diazotisation? Convert aniline to benzene diazonium chloride, and the salt to (i) bromobenzene and (ii) phenol.
Diazotisation: the conversion of a primary aromatic amine into a diazonium salt by nitrous acid at 0 to 5 °C. Nitrous acid is generated in situ from sodium nitrite and hydrochloric acid.
Aniline to benzene diazonium chloride: C6H5NH2 + NaNO2 + 2HCl → C6H5N2+Cl− + NaCl + 2H2O (0 to 5 °C). The salt is an intermediate for many aromatic compounds.
(i) Bromobenzene (Sandmeyer reaction): treat the salt with cuprous bromide in hydrobromic acid: C6H5N2+Cl− → C6H5Br + N2 (CuBr/HBr). Nitrogen gas is evolved.
(ii) Phenol: warm the salt with water or dilute acid: C6H5N2+Cl− + H2O → C6H5OH + N2 + HCl. Nitrogen gas is again liberated.
Conclusion: aniline is diazotised with NaNO2 and HCl at 0 to 5 °C, and the diazonium salt then gives bromobenzene through the Sandmeyer route and phenol through warm hydrolysis.
DNA vs RNA, transcription and translation
Question: What are the major differences between DNA and RNA? Briefly explain transcription and translation.
| Feature | DNA | RNA |
|---|---|---|
| Sugar | Deoxyribose | Ribose |
| Bases | Adenine, guanine, cytosine, thymine | Adenine, guanine, cytosine, uracil |
| Strands | Usually double-stranded | Usually single-stranded |
| Location | Mainly nucleus, also mitochondria and chloroplasts | Nucleus and cytoplasm |
| Function | Stores and passes on genetic information | Takes part in protein synthesis |
| Stability | More stable | Less stable |
Transcription: DNA unwinds and one strand acts as a template, RNA polymerase binds to it, complementary ribonucleotides join to form mRNA, and the mRNA leaves for the cytoplasm. Genetic information passes from DNA to mRNA.
Translation: mRNA attaches to a ribosome, tRNA brings specific amino acids, tRNA anticodons pair with mRNA codons, and the amino acids join through peptide bonds to form a polypeptide that folds into a protein. The genetic code is read as triplet codons, each naming an amino acid or a stop signal.
Conclusion: DNA and RNA differ in sugar, bases, strands, location and role, and the genetic code is expressed when DNA is transcribed into mRNA and mRNA is translated into protein.
These five show the standard of all 13. The remaining 8 answers, including ozonolysis, Cannizzaro vs aldol and Sanger's end-group method, are in the full file.
3. CHE 05 Important Questions Found in Six Past Papers
Across the June 2023 to December 2025 papers, DNA vs RNA appeared in 5 of 6 sessions, and Hückel's rule, ozonolysis, Grignard reagent, Hofmann bromamide, end-group analysis and saponification value each appeared in 4. These are the CHE 05 important questions that decide how the long-answer sections are set.
We did not guess from memory. Each session's paper was read part by part and every topic was ticked against its session. You can open the same papers yourself on our IGNOU Previous Year Question Paper page and check our counts against each session.
| Topic | Unit | Sessions seen | Where it sits |
|---|---|---|---|
| R/S and E/Z configuration | 2 to 3 | 6 of 6 | Question 1 skill item, practise on new molecules |
| UV, IR and NMR spectroscopy basics | Across blocks | 6 of 6 | Questions 1 and 2 short parts, count proton types |
| Acidity and basicity comparison | 5 | 5 of 6 | Short reasoning parts, phenol vs methanol type |
| SN reactions, Saytzeff rule, E2 | 11 | 5 of 6 | Mechanism parts, draw the arrows |
| DNA vs RNA and genetic code | 20 | 5 of 6 | Sample 5 on this page |
| Aromaticity and Hückel's rule | 9 | 4 of 6 | Sample 1 on this page |
| Ozonolysis of alkenes | 7 | 4 of 6 | Full file, but-1-ene vs but-2-ene table |
| Grignard reagent | 11 | 4 of 6 | Sample 2 on this page |
| Hofmann bromamide or Gabriel synthesis | 17, 19 | 4 of 6 | Full file, acetamide to methylamine |
| End-group analysis (Sanger, carboxypeptidase) | 20 | 4 of 6 | Full file, FDNB and DNP derivative |
| Saponification value, iodine value, soaps | 20 | 4 of 6 | Full file, micelle cleansing action |
| Pyridine vs pyrrole basicity | 10 | 3 of 6 | Full file, lone pair and aromatic sextet |
| Haloform or iodoform test | 14 | 3 of 6 | Sample 3 on this page |
| Reduction of nitrobenzene in three media | 18 | 3 of 6 | Full file, acid vs neutral vs alkaline table |
| Cannizzaro and aldol condensation | 14 | 2 of 6 (both 2025 sessions) | Full file, α-hydrogen rule explained |
| Diazotisation and diazonium salts | 19 | 2 of 6 | Sample 4 on this page |
| Mutarotation and anomers of glucose | 20 | 1 of 6 | Full file, +112° to +52.7° rotation |
Notice the gap. The six most frequent topics include R/S configuration and spectroscopy, which cannot be guessed as fixed answers. The full file covers the long-answer topics, and the exam plan below tells you how to practise the Q1 skill items separately.
4. CHE 05 Organic Chemistry Syllabus: 4 Blocks and 20 Units
CHE-05 Organic Chemistry has 4 blocks and 20 units: Fundamental Concepts (Units 1 to 5), Hydrocarbons and Heterocycles (6 to 10), Derivatives of Hydrocarbons I (11 to 14) and Derivatives of Hydrocarbons II (15 to 20). The block names follow the official course books on eGyanKosh.
| Block | Unit | Unit title | Topics that carry marks |
|---|---|---|---|
| Block 1: Fundamental Concepts | 1 | Bonding, Functional Group Classification and Nomenclature | IUPAC names, hybridisation, functional-group families |
| Block 1: Fundamental Concepts | 2 | Stereochemistry I | Optical isomerism, R/S priority rules, enantiomers vs diastereomers |
| Block 1: Fundamental Concepts | 3 | Stereochemistry II | Conformations of ethane and cyclohexane, E/Z geometric isomers |
| Block 1: Fundamental Concepts | 4 | Effect of Molecular Architecture on Physical Properties | Hydrogen bonding, boiling point trends, maleic vs fumaric dipole moment |
| Block 1: Fundamental Concepts | 5 | Structure Reactivity Relationships | Inductive and resonance effects, hyperconjugation, acid strength order |
| Block 2: Hydrocarbons and Heterocycles | 6 | Alkanes | Free-radical halogenation, Wurtz reaction, cetane number |
| Block 2: Hydrocarbons and Heterocycles | 7 | Alkenes | Markovnikov and peroxide effect, ozonolysis, propene to n-propanol |
| Block 2: Hydrocarbons and Heterocycles | 8 | Alkynes | Acidity of terminal alkynes, hydration to carbonyl compounds |
| Block 2: Hydrocarbons and Heterocycles | 9 | Aromatic Hydrocarbons and Polynuclear Aromatics | Hückel's rule, Friedel-Crafts reactions, naphthalene nitration and oxidation |
| Block 2: Hydrocarbons and Heterocycles | 10 | Heterocyclic Compounds | Pyridine vs pyrrole basicity, substitution positions in pyridine |
| Block 3: Derivatives of Hydrocarbons I | 11 | Halogen Derivatives | SN1 and SN2, Saytzeff elimination, Grignard reagent |
| Block 3: Derivatives of Hydrocarbons I | 12 | Alcohols and Phenols | Phenol vs methanol acidity, glycol to oxalic acid, benzene to phenol |
| Block 3: Derivatives of Hydrocarbons I | 13 | Ethers and Sulphur Analogues of Alcohols and Ethers | Williamson synthesis, crown ethers, thiols and thioethers |
| Block 3: Derivatives of Hydrocarbons I | 14 | Aldehydes and Ketones | Aldol condensation, Cannizzaro reaction, iodoform test |
| Block 4: Derivatives of Hydrocarbons II | 15 | Monocarboxylic and Sulphonic Acids | Effect of substituents on acid strength, sulphonic acid reactions |
| Block 4: Derivatives of Hydrocarbons II | 16 | Substituted Carboxylic Acids | Halo and hydroxy acids, behaviour of dicarboxylic acids on heating |
| Block 4: Derivatives of Hydrocarbons II | 17 | Functional Derivatives of Monocarboxylic Acids | Acid chlorides, esters, amides, Hofmann bromamide reaction |
| Block 4: Derivatives of Hydrocarbons II | 18 | Nitro Compounds | Nitrobenzene reduction in three media, nitro-aci tautomerism |
| Block 4: Derivatives of Hydrocarbons II | 19 | Amino Compounds and Diazonium Salts | Amines with HNO2, diazotisation, Sandmeyer reaction |
| Block 4: Derivatives of Hydrocarbons II | 20 | Natural Products | Glucose mutarotation, Sanger's method, DNA vs RNA, fats and soaps |
Block 4 is the heaviest in marks. Units 19 and 20 alone produced diazonium, amine, peptide, nucleic acid and fat questions in every session we checked, which is why 7 of the 13 answers in this CHE 05 Guess Paper come from Block 4.
5. Full Question Index of the CHE 05 Guess Paper
The file holds 13 solved questions; 5 are shown on this page and the remaining 8 unlock when you order. Use this index to see exactly what is inside before you message us.
| No. | Question topic | Unit | Marks | On this page? |
|---|---|---|---|---|
| Q1 | Aromaticity and Hückel's rule | 9 | 3 | Yes, Sample 1 |
| Q2 | Ozonolysis and locating the double bond | 7 | 4 | Full file |
| Q3 | Pyridine vs pyrrole basicity | 9 to 10 | 3 | Full file |
| Q4 | Grignard reagent preparation and uses | 11 | 4 | Yes, Sample 2 |
| Q5 | Cannizzaro vs aldol condensation | 14 | 4 | Full file |
| Q6 | Haloform and iodoform test | 14 | 3 | Yes, Sample 3 |
| Q7 | Reduction of nitrobenzene in acid, neutral and alkaline media | 18 | 4 | Full file |
| Q8 | Diazotisation and diazonium salt conversions | 19 | 4 | Yes, Sample 4 |
| Q9 | Hofmann bromamide rearrangement | 17 to 19 | 3 | Full file |
| Q10 | Mutarotation and anomers of glucose | 20 | 3 | Full file |
| Q11 | End-group analysis by Sanger's method and carboxypeptidase | 20 | 4 | Full file |
| Q12 | DNA vs RNA, transcription and translation | 20 | 4 | Yes, Sample 5 |
| Q13 | Saponification value, iodine value and soap action | 20 | 4 | Full file |
6. CHE 05 Organic Chemistry Practical File Index
CHE-05 itself is a theory course with no separate practical exam, but its reactions are the same ones you test at the bench in the B.Sc. chemistry lab course. This index links each common organic experiment to the CHE-05 unit it comes from, so your theory and your lab record support each other.
| No. | Experiment | CHE-05 unit | What the record page shows |
|---|---|---|---|
| 1 | Lassaigne's test for nitrogen, sulphur and halogens | 1 | Sodium fusion extract, Prussian blue and silver halide results |
| 2 | Melting point and boiling point determination | 4 | Capillary method readings and purity check |
| 3 | Tests for unsaturation | 7 to 8 | Bromine water decolourisation, Baeyer's reagent colour change |
| 4 | Test for phenolic –OH group | 12 | Neutral ferric chloride violet colour |
| 5 | 2,4-DNP test for carbonyl group | 14 | Orange-yellow hydrazone precipitate |
| 6 | Tollens' and Fehling's tests | 14 | Silver mirror and red precipitate, aldehyde vs ketone |
| 7 | Iodoform test | 14 | Yellow CHI3 precipitate for –COCH3 compounds |
| 8 | Sodium bicarbonate test for carboxylic acids | 15 | Brisk effervescence of CO2 |
| 9 | Carbylamine test for primary amines | 19 | Offensive isocyanide smell, safety note |
| 10 | Azo dye test for aromatic primary amines | 19 | Orange-red dye with β-naphthol after diazotisation at 0 to 5 °C |
| 11 | Molisch's test for carbohydrates | 20 | Violet ring at the junction of two layers |
| 12 | Preparation of soap by saponification | 20 | Fat plus NaOH, salting out and lather check |
If you also need a written practical record for your lab course, ask about it when you message us on WhatsApp for the guess paper. Mention your programme and lab course code so we send the right file.
7. CHE 05 Exam Pattern and Answer Plan
The CHE-05 term-end paper carries 50 marks in 2 hours, with four compulsory questions: five 1-mark parts, then any five of six parts at 2, 3 and 4 marks. The pattern matches the official December 2022 CHE-05 paper on the IGNOU website, and the later sessions we analysed follow the same layout.
| Question | Parts to answer | Marks | Typical content | Time to spend |
|---|---|---|---|---|
| Question 1 | All 5 | 5 × 1 = 5 | IUPAC name, dipole moment, auxochromes, proton count | 8 minutes |
| Question 2 | Any 5 of 6 | 5 × 2 = 10 | Conversions like propene to isopropanol, acid strength reasons | 20 minutes |
| Question 3 | Any 5 of 6 | 5 × 3 = 15 | Hückel's rule, iodoform test, pyridine vs pyrrole, mutarotation | 35 minutes |
| Question 4 | Any 5 of 6 | 5 × 4 = 20 | Grignard, diazonium salts, nitrobenzene media, DNA vs RNA | 50 minutes |
That leaves about 7 minutes to recheck arrows and conditions. In Questions 2 to 4 you drop one part each, so pick the ones where you can write the full reaction. A half-written reaction usually scores less than a complete shorter answer.
For Question 1, no guess paper can hand you the answer, because the molecule changes every session. Practise R/S assignment and IUPAC naming on the structures in any two past papers, and use Organic Chemistry important questions from Blocks 2 to 4 for the long parts.
8. Who Should Buy the CHE 05 Guess Paper and How to Order
This file suits B.Sc. students under BDP who take CHE-05 as a chemistry elective and want complete, mark-sized answers for the December 2026 exam. It also works well for learners repeating the paper who need to see where their earlier answers fell short.
It is not the right buy if you are on the newer semester-based B.Sc. General programme, because that scheme uses BCHCT chemistry courses instead of CHE-05. For those papers, look at our BSCG guess Paper range, and browse every code we cover on the IGNOU Solved Guess Paper hub.
Ordering takes a minute. Message us on WhatsApp at 9899436384 with the code CHE-05, confirm your programme, and complete the payment we share. The PDF arrives on the same chat once payment is confirmed, and the same number handles any doubt about an answer later.
9. CHE 05 Organic Chemistry Guess Paper FAQs
What is included in the CHE 05 guess paper from Unnati Educations?
The CHE 05 guess paper is a 16-page PDF with 13 fully solved long-answer questions from Blocks 2, 3 and 4 of Organic Chemistry. Each answer carries its unit tag, past sessions, marks and a word target, and writes out every reaction with reagents and conditions. The file also includes exam rules and a six-session topic frequency grid covering June 2023 to December 2025.
How many questions of the CHE 05 guess paper can I see before buying?
You can read 5 complete answers on this page: Hückel's rule, Grignard reagent, the iodoform test, diazotisation and DNA vs RNA. That is 5 of the 13 questions in the file. The remaining 8, covering ozonolysis, pyridine vs pyrrole, Cannizzaro vs aldol, nitrobenzene reduction, Hofmann bromamide, mutarotation, end-group analysis and soaps, come with the full PDF.
Which past papers were used to build the IGNOU CHE 05 guess paper?
We analysed six IGNOU term-end sessions for CHE-05: June 2023, December 2023, June 2024, December 2024, June 2025 and December 2025. Every topic was ticked against the sessions it appeared in, and those counts decided which 13 questions made the file. You can check the same papers on the official IGNOU question paper archive or our previous year paper page.
Is CHE 05 Organic Chemistry part of the IGNOU BSc General programme?
CHE-05 Organic Chemistry belongs to the IGNOU Bachelor of Science under the Bachelor's Degree Programme (BDP), where it is taken as a chemistry elective from the School of Sciences. The newer semester-based B.Sc. General programme uses BCHCT course codes for chemistry instead. If your hall ticket or assignment list shows CHE-05, this guess paper matches your exam.
What is the exam pattern for IGNOU CHE 05 Organic Chemistry?
The CHE-05 term-end exam is 50 marks and runs for 2 hours. All four questions are compulsory. Question 1 has five 1-mark parts, and Questions 2, 3 and 4 each ask you to attempt any five of six parts worth 2, 3 and 4 marks. A 4-mark answer needs about 230 words, and a 3-mark answer about 170 words.
Are CHE 05 important questions enough to pass without reading the books?
No, and we would not advise it. The CHE 05 important questions in our file cover the long-answer sections well, but Question 1 tests skills such as R/S assignment and IUPAC naming on new molecules each session. Use the guess paper for the 45 marks of Questions 2 to 4 and practise Question 1 skills from the unit books and past papers.
How do I get the full CHE 05 guess paper PDF?
Send a WhatsApp message to 9899436384 with the course code CHE-05 and your programme name. Our team confirms the price and payment details on the same chat, and the complete PDF with all 13 solved questions is shared there as soon as payment is confirmed. The same number stays open for doubts about any answer right up until your exam day.
10. Who Prepared the CHE 05 Guess Paper
The CHE-05 file was written by the Unnati Educations IGNOU team under Prateek Talwar and reviewed by Sheetal Kirola before release. Both work with IGNOU learners at our Vikaspuri, Delhi centre and handle the study-material line for B.Sc., BA and postgraduate codes.
Prateek Talwar leads content at Unnati Educations and sets the answer format used across our guess papers. LinkedIn · Instagram
Sheetal Kirola heads administration and checks every IGNOU file for accuracy, length and syllabus fit before it reaches students. LinkedIn · Instagram · Facebook