BCHCT 131 Solved Guess Paper 2026 is a 16 page answer file carrying 12 high probability questions with complete written solutions, prepared by the Unnati Educations chemistry desk after reading five consecutive IGNOU term end papers from December 2023 through to December 2025. Every question in the file is mapped to a block, carries its marks split, and is answered the way a scriptmarker expects to see it, with the rule stated first and the structure or mechanism drawn immediately after.
Five of those twelve questions are printed in full on this page, with answers, so you can judge the writing quality before you pay anything. Six page previews from the actual PDF are shown further down. The remaining seven questions are delivered on WhatsApp.
BCHCT 131 at a Glance
| Course: | Atomic Structure, Bonding, General Organic Chemistry and Aliphatic Hydrocarbons |
|---|---|
| Programmes: | Bachelor of Science (BSCG), Bachelor of Science (BSCM, Multidisciplinary under FYUP), Bachelor of Science Honours Biochemistry (BSCBCH) |
| Credits: | 4 theory credits, roughly 120 study hours |
| Structure: | 4 blocks, 19 units |
| Term end exam: | 2 hours, 50 marks, two parts of 25 marks each |
| Attempt rule: | any five questions per part, 5 marks each |
| Guess paper size: | 12 questions, 16 pages of answers |
| Papers analysed: | 5 sessions, December 2023 to December 2025 |
| Target sessions: | June 2026 and December 2026 |
What the BCHCT 131 Solved Guess Paper 2026 Includes and How It Was Built
The file contains 12 questions across 16 pages, each one carrying a verbatim IGNOU style question, a marks split, a block tag and a complete model answer. Nothing in it is a summary or a bullet dump. Each answer opens with the governing definition and its attribution, works through the parts in the order the examiner asks for them, and closes with a short conclusion paragraph you can reproduce as your final two lines in the answer book.
The selection method was deliberately narrow. We pulled the December 2023, June 2024, December 2024, June 2025 and December 2025 papers, tabulated every topic that appeared in each, and then applied frequency gap logic.
A topic that surfaced in four or five of those five sittings went straight in. A topic that surfaced twice, with a two session gap since its last appearance, also went in on the reasoning that the rotation is due. Topics that appeared once in five sittings were left out, and we say so plainly inside the file rather than padding the page count.
The result covers all four blocks rather than clustering in the easy ones. Block 1 contributes Bohr's postulates, the de Broglie calculation and quantum numbers. Block 2 contributes VSEPR shapes, molecular orbital bond order for the oxygen species, resonance and ionisation energy.
Block 3 contributes stereochemistry, acid strength ordering and conformational analysis, while Block 4 contributes aromaticity, ozonolysis and Markovnikov addition. If you are building a wider revision set, the same counting method sits behind every IGNOU Solved Guess Paper we publish for other course codes.
Answers are written in plain English with the chemistry kept precise. Where a numerical is involved, the substitution line is shown before the result, because IGNOU markers award the working. Where a mechanism is involved, the intermediate is named and justified, so you are not memorising an arrow diagram you cannot explain.
Five Sample Questions with Full Answers from the BCHCT 131 Guess Paper
Five of the twelve questions are reproduced below in full, one from Block 1, one from Block 2, two from Block 3 and one from Block 4. They are printed exactly as they appear in the file, with no shortening. Read the conclusion lines in particular, since those are the sentences that convert a half answer into a full five mark answer.
Sample 1 Β· Bohr's Postulates and de Broglie Wavelength Β· Block 1 Β· 5 Marks
Question. (a) State the main postulates of Bohr's atomic model. Also list any two limitations of this theory. (3 marks)
(b) Calculate the de Broglie wavelength associated with an electron of mass 9.109 Γ 10β»Β³ΒΉ kg moving with a velocity of 2.19 Γ 10βΆ m sβ»ΒΉ. (2 marks)
Answer, Part (a). Bohr (1913): an electron can exist only in orbits of definite angular momentum and energy.
- Stationary states. Electrons exist only in orbits of definite angular momentum and energy.
- No radiation. While in an allowed orbit, the electron does not radiate energy.
- Quantisation. mvr = nh/2Ο, where n = 1, 2, 3, β¦
- Spectral lines. Emitted or absorbed when an electron jumps orbits; ΞE = hΞ½.
Two limitations. It fails to explain the spectra of multi-electron atoms, and it ignores the wave nature of the electron, violating Heisenberg's uncertainty principle.
Answer, Part (b). Ξ» = h / mv. With m = 9.109 Γ 10β»Β³ΒΉ kg, v = 2.19 Γ 10βΆ m sβ»ΒΉ and h = 6.626 Γ 10β»Β³β΄ J s:
Ξ» = (6.626 Γ 10β»Β³β΄) / (9.109 Γ 10β»Β³ΒΉ Γ 2.19 Γ 10βΆ) β 3.32 Γ 10β»ΒΉβ° m = 3.32 Γ
Conclusion. Bohr's postulates explain hydrogen's line spectrum but fail for multi-electron atoms. de Broglie's Ξ» = h/mv unites particle and wave; here Ξ» β 3.32 Γ , comparable to atomic dimensions.
Sample 2 Β· Molecular Orbital Theory, Bond Order and Magnetism of Oβ Species Β· Block 2 Β· 5 Marks
Question. (a) Write the molecular orbital electronic configuration of Oββ» ion. Calculate its bond order and explain its magnetic behaviour. (3 marks)
(b) Explain why OββΊ is paramagnetic while OβΒ²βΊ is diamagnetic. (2 marks)
Answer, Part (a). Bond Order = Β½ (Nb β Na), where Nb and Na are bonding and antibonding electrons. Oββ» has 17 electrons:
(Ο1s)Β² (Ο*1s)Β² (Ο2s)Β² (Ο*2s)Β² (Ο2pβ)Β² (Ο2py)Β² (Ο2pz)Β² (Ο*2py)Β² (Ο*2pz)ΒΉ
Nb = 10, Na = 7, so BO = Β½(10 β 7) = 1.5. One unpaired electron in the Ο* set makes it weakly paramagnetic.
| Species | Total eβ» | Unpaired eβ» | Magnetism | Bond order |
|---|---|---|---|---|
| Oβ | 16 | 2 | Paramagnetic | 2.0 |
| OββΊ | 15 | 1 | Paramagnetic | 2.5 |
| OβΒ²βΊ | 14 | 0 | Diamagnetic | 3.0 |
| Oββ» | 17 | 1 | Paramagnetic | 1.5 |
Conclusion. Oββ»: BO 1.5, paramagnetic. OββΊ: BO 2.5, paramagnetic. OβΒ²βΊ: BO 3.0, diamagnetic, since the Ο* orbitals are empty. Adding electrons to Ο* lowers bond order; removing them raises it.
Sample 3 Β· Stereochemistry, R and S Configuration and Optical Isomers Β· Block 3 Β· 5 Marks
Question. (a) State the CIP (CahnβIngoldβPrelog) priority rules and assign the R or S configuration to glyceraldehyde-type structure CHO β C*(OH)(H) β CHβOH. (3 marks)
(b) Distinguish between enantiomers, diastereomers and a meso compound, with one example of each. (2 marks)
Answer, Part (a). Cahn, Ingold and Prelog (1956): substituents at the chiral centre are ranked by atomic number to assign R or S.
- Atomic number. Higher Z means higher priority (O > N > C > H).
- First point of difference. For ties, move outward atom by atom.
- Multiple bonds. A double bond counts as a duplicated atom, a triple as triplicated.
- Isotopes. Heavier isotope outranks lighter (Β²H > ΒΉH).
Priorities: OH (1) > CHO (2) > CHβOH (3) > H (4). With H pointing away, OH β CHO β CHβOH traces clockwise, giving R. Hence D-(+)-glyceraldehyde is (R)-glyceraldehyde.
Answer, Part (b). Enantiomers are non-superimposable mirror images, for example (+)- and (β)-tartaric acid. Diastereomers are stereoisomers that are not mirror images, for example (+)-tartaric acid against meso-tartaric acid. A meso compound has stereocentres but an internal mirror plane, so it is optically inactive, for example meso-tartaric acid.
Conclusion. CIP rules rank substituents by atomic number. D-(+)-glyceraldehyde is (R). Enantiomers are mirror images, diastereomers are not, and meso compounds are optically inactive through internal compensation.
Sample 4 Β· Acid Strength Order with Reasons Β· Block 3 Β· 5 Marks
Question. (a) Arrange the following carboxylic acids in increasing order of acid strength and explain your answer: CHβCOOH, ClCHβCOOH, ClβCHCOOH, ClβCCOOH. (3 marks)
(b) Identify the stronger acid in each pair and give brief reasons: (i) ClCHβCHβCOOH vs CHβCHClCOOH; (ii) HCOOH vs CHβCOOH. (2 marks)
Answer, Part (a). The polarisation of a chain of atoms linked by Ο-bonds is the inductive effect.
Order: CHβCOOH < ClCHβCOOH < ClβCHCOOH < ClβCCOOH, with pKa values 4.76, 2.86, 1.30 and 0.65 respectively.
- Chlorine is electron withdrawing. Each Cl exerts a βI effect on the Ξ±-carbon, pulling Ο-electron density away.
- Conjugate base stability. That withdrawal disperses the negative charge of RCOOβ», stabilising the anion and strengthening the acid.
- Cumulative effect. Each successive Cl adds a further βI withdrawal, so trichloroacetic acid is strongest.
Answer, Part (b). CHβCHClCOOH > ClCHβCHβCOOH, because the Ξ±-chloro substituent sits closer to COOH and the βI effect attenuates rapidly with distance. HCOOH > CHβCOOH, because the methyl group of acetic acid is electron donating (+I) and destabilises the carboxylate anion.
Conclusion. βI groups stabilise RCOOβ» and strengthen the acid; +I groups destabilise it and weaken the acid. Hence CHβCOOH < ClCHβCOOH < ClβCHCOOH < ClβCCOOH, with Ξ±-chloro above Ξ²-chloro and HCOOH above CHβCOOH.
Sample 5 Β· Markovnikov and Anti-Markovnikov Addition Β· Block 4 Β· 5 Marks
Question. (a) State Markovnikov's rule and give the mechanism of: CHββCH=CHβ + HBr β CHββCHBrβCHβ. (3 marks)
(b) What is the peroxide effect (Kharasch effect)? Give the product and the radical-chain mechanism for: CHββCH=CHβ + HBr (in the presence of organic peroxide). (2 marks)
Answer, Part (a). Markownikoff's rule: when HX adds to an unsymmetrical alkene, H goes to the carbon carrying more hydrogens and X goes to the more substituted carbon.
Step 1. The Ο-electrons attack the H of HBr. Protonation of the terminal CHβ generates the more stable secondary carbocation CHββCHβΊβCHβ, preferred over the primary CHββCHββCHββΊ.
Step 2. Brβ» captures the carbocation, giving 2-bromopropane.
Answer, Part (b). With peroxide (ROOR) present, HBr adds anti-Markovnikov to give 1-bromopropane. The effect operates only with HBr, not with HCl or HI.
Initiation. ROOR β 2 ROβ’; ROβ’ + HBr β ROH + Brβ’.
Propagation 1. Brβ’ adds to the terminal CHβ of CHβ=CHCHβ, giving the more stable secondary radical CHββCHβ’βCHβBr.
Propagation 2. That carbon radical abstracts H from HBr, giving CHββCHββCHβBr and regenerating Brβ’.
Conclusion. The ionic route favours the secondary carbocation, so HBr and propene give 2-bromopropane. With peroxides, the Kharasch and Mayo radical chain gives 1-bromopropane. The peroxide effect operates only with HBr.
Seven more solved questions of this standard are waiting in the full file. WhatsApp 9899436384 to get the complete 16 page PDF.
BCHCT 131 Block and Unit Index Covering All 19 Units
BCHCT 131 is built from 4 blocks holding 19 units in total, and the guess paper draws from all four. The table below is the full unit index with the specific concepts each unit is examined on, so you can see exactly which part of the syllabus every guess paper question maps back to.
| Block | Unit | Unit title | Concepts examined from this unit | 2026 priority |
|---|---|---|---|---|
| Block 1: Atomic Structure | 1 | Bohr's Theory | Dalton's postulates, Bohr's four postulates, radius and energy of the nth orbit, spectral series | High |
| 2 | Dual Behaviour of Radiation and Matter | de Broglie relation and numericals, Heisenberg uncertainty principle, photoelectric effect | High | |
| 3 | Quantum Mechanical Approach | SchrΓΆdinger equation, operators and eigenvalues, well behaved wave functions | Medium | |
| 4 | Hydrogen Atom | Spherical polar coordinates, radial and angular functions, shapes of s, p and d orbitals, nodes | Medium | |
| 5 | Electronic Configuration of Multi-Electron Atoms | Four quantum numbers, Aufbau, Hund and Pauli, Cr and Cu anomalies, ionisation energy and electron affinity trends | High | |
| Block 2: Chemical Bonding and Molecular Structure | 6 | Ionic Bond | Lattice energy, Born Haber cycle, Fajans rules, polarising power and ionic character | Medium |
| 7 | Covalent Bond | Lewis structures of HCN, COβΒ²β» and SFβ, VSEPR shape prediction, dipole moment, resonance | High | |
| 8 | Valence Bond Theory | Orbital overlap, sp, spΒ² and spΒ³ hybridisation, hybridisation involving d orbitals, bond angles | High | |
| 9 | Molecular Orbital Theory | LCAO, MO diagrams for Oβ, Nβ and their ions, bond order calculation, paramagnetism against diamagnetism | High | |
| Block 3: Fundamentals of Organic Chemistry | 10 | Stereochemistry I: Geometrical and Optical Isomerisms | Cis and trans, E and Z assignment, chirality, plane polarised light and specific rotation | Medium |
| 11 | Stereochemistry II: Configurational Isomers | CIP priority rules, R and S assignment, enantiomers, diastereomers, meso compounds, Fischer projections | High | |
| 12 | Stereochemistry III: Conformational Isomerism | Newman and sawhorse projections, ethane and n-butane conformers, chair against boat cyclohexane | High | |
| 13 | Structure-Reactivity Relationships | Inductive, resonance and hyperconjugative effects, acid and base strength ordering, pKa reasoning | High | |
| 14 | Reactions and Reactive Intermediates | Carbocation, carbanion and free radical stability, electrophiles and nucleophiles, curly arrow notation | Medium | |
| Block 4: Hydrocarbons | 15 | Alkanes | Preparation methods, free radical halogenation mechanism, conformations and relative stability | Medium |
| 16 | Alkenes I | Preparation and elimination routes, Markovnikov addition, carbocation rearrangement | High | |
| 17 | Alkenes II | Peroxide effect, hydroboration oxidation, ozonolysis and structure determination, oxidation reactions | High | |
| 18 | Alkynes | Acidity of terminal alkynes, Lindlar and Birch reduction, ozonolysis of but-2-yne, hydration | Medium | |
| 19 | Aromaticity | HΓΌckel's (4n + 2) rule, cyclopentadienyl anion and cation, cyclobutadiene, naphthalene and anthracene | High |
One point worth clearing up, because students ask it every session. BCHCT 131 is a theory only course, so there is no practical file to submit for it. The laboratory work that pairs with this syllabus sits in the separate 2 credit course BCHCL 132, which has its own lab manual, its own record file and its own practical examination. If you are hunting for that record file, look under BCHCL 132 and not here.
Five Session Frequency Analysis Behind Each BCHCT 131 Question
Every question in the file earned its place by appearing in at least two of the last five term end papers, and most appeared in four or five. That is the whole basis of the selection. We did not guess what feels important; we counted what actually recurred.
Electronic configuration, Lewis structures and acid strength ordering were the three topics to appear in all five sittings, which is why each is treated at full length inside the file. Molecular orbital bond order, VSEPR, quantum numbers and electron affinity each appeared in four.
Aromaticity and HΓΌckel's rule ran through four consecutive sittings between December 2023 and June 2025, then dropped out in December 2025. That absence is exactly the frequency gap that makes the topic likely in 2026 rather than unlikely, so it stays in the file.
At the other end, blackbody radiation, eigenfunction definitions and the rarer named reactions such as Sabatier-Senderens appeared once across five papers. Those are named inside the file as low return topics, with a short note on why we left them out, so you can stop worrying about them.
If you would like to run the counting yourself, every original paper is listed on our IGNOU Previous Year Question Paper hub.
IGNOU also publishes these papers directly, and the December 2023 sitting used for the pattern details on this page can be read on the official IGNOU question paper archive.
BCHCT 131 Exam Pattern, Marks Split and Two Hour Answer Plan
The term end paper runs 2 hours for 50 marks, split into two parts of 25 marks each, written in two separate answer books. Each part asks you to attempt any five questions worth 5 marks apiece. Sub-part splits are usually 3 plus 2, sometimes 4 plus 1 or 2 plus 2 plus 1.
That arithmetic matters more than students realise. Ten answers in 120 minutes leaves you about 11 minutes per answer once you allow for reading and enrolment details. Every model answer in the file is written to that length, so what you practise is what you can actually reproduce in the hall.
Trying to write a 25 minute answer for a 5 mark question is the commonest way BSCG chemistry students run out of time in Part 2. Once you have finished the guess paper, work through a past BCHCT 131 Question paper under clock conditions to test the pacing for yourself.
One practical instruction from the paper itself is easy to miss under pressure. The two parts go into two separate answer books, and your enrolment number, course code and part title must be written on each. Marks have been lost on that alone.
Who This BCHCT 131 Guess Paper Is For Across BSCG, BSCM and BSCBCH
BCHCT 131 is a discipline specific core course, so the same paper is written by students in three different programmes. It appears in Bachelor of Science (BSCG), in Bachelor of Science (BSCM, the multidisciplinary route under FYUP), and in Bachelor of Science Honours Biochemistry (BSCBCH). The syllabus, the block structure and the term end paper are identical in all three, so this file serves all of them without modification.
For BSCG chemistry students this is usually the first chemistry paper of the degree, and the atomic structure block tends to be the shock, because the maths arrives faster than expected. If you are assembling a full semester set, the companion BSCG guess Paper collection covers the other core codes you will sit alongside this one.
Biochemistry Honours students often come to this paper with stronger organic chemistry than physical chemistry, which flips the difficulty. For that group, Blocks 1 and 2 need the extra hours, and the wider BSCBCH guess Paper set is worth looking at once this code is done. Students repeating the paper after a back attempt tend to find the frequency grid the most useful page in the file, because it tells them where their earlier revision was misallocated.
How to Order the BCHCT 131 Solved Guess Paper on WhatsApp
Send the course code BCHCT 131 on WhatsApp to 9899436384 and the complete 16 page PDF is shared with you digitally. There is no account to create and no waiting for a courier, since delivery is a file, not a book.
What arrives is the full set of 12 solved questions, the block wise mapping, the marks split for each question, the five session frequency grid, the examiner guidance page and the list of low return topics to skip. The five samples above are already part of that 12, so what is new to you is the remaining seven. Ask any question you like about the file before you decide, including sending back a specific topic to check whether it is covered.
The Seven BCHCT 131 Important Questions Kept Inside the Full File
Here are the exact seven questions not printed on this page, so you know precisely what you are getting rather than buying blind. Each is answered at the same length and in the same format as the five samples above.
- Quantum numbers for a 3d orbital, plus the Cr and Cu configuration anomalies and the exchange energy reasoning behind them. Block 1.
- VSEPR shape prediction for SFβ and NHβ with structures drawn, plus Lewis structures of HCN and COβΒ²β». Block 2.
- All contributing resonance structures of NOββ» and aniline, with the reasoning for which canonical form contributes most. Block 2.
- Ionisation energy definition and the Be, B, N, O ordering with reasons, plus why nitrogen has a positive electron affinity and carbon a large negative one. Block 2.
- HΓΌckel's rule applied to the cyclopentadienyl anion and cation, cyclobutadiene and benzene, with examples of bicyclic and 14 Ο electron aromatics. Block 4.
- Ozonolysis working backwards from acetone and ethyl methyl ketone to the parent alkene, plus ozonolysis products of but-2-yne and but-2-ene. Block 4.
- Newman projections of eclipsed and anti n-butane with energy reasoning, plus chair against boat cyclohexane and flagpole interactions. Block 3.
A Ten Day Revision Plan Using the BCHCT 131 Guess Paper
Ten days is enough for this paper if you spend the first six on Blocks 1 and 2, which carry the numericals and the diagrams. The organic half rewards pattern recognition and moves faster once the physical half is secure.
Days 1 and 2 go to atomic structure: Bohr's postulates written out from memory, the de Broglie substitution practised three times with different values, quantum numbers tabulated. Days 3 and 4 go to bonding: draw every Lewis structure by hand, count electron pairs before naming any VSEPR shape, and build the Oβ molecular orbital diagram until you can produce it without the book.
Days 5 and 6 cover resonance, ionisation energy and electron affinity, which are quick marks once the reasoning is fluent. Days 7 and 8 take stereochemistry and acid strength, both of which need pen work rather than reading. Days 9 and 10 take Blocks 4 mechanisms, ozonolysis and aromaticity, then one full timed attempt at 10 questions in 120 minutes. Do not skip the timed attempt.
Authors, Review and Official Sources Used for BCHCT 131
The answers were written by Prateek Talwar, founder of Unnati Educations, and academically reviewed by Sheetal Kirola, M.Ed. Between them they have prepared IGNOU and university examination material for students across Delhi since the platform started, and the chemistry answers here were checked line by line against the official block material rather than written from memory.
The course facts stated on this page come from IGNOU directly. Credit weight, block count and the 19 unit structure are taken from the IGNOU School of Sciences B.Sc. Chemistry course page and the official block PDFs hosted on eGyanKosh. The exam pattern, marks and attempt rule are taken from the printed instructions on IGNOU's own December 2023 BCHCT 131 question paper, linked in the frequency section above. Where a claim could not be traced to an IGNOU source, it is not on this page.
Ready to get the complete file? WhatsApp 9899436384 with the code BCHCT 131 and we will send the 16 page PDF across.
BCHCT 131 Guess Paper Frequently Asked Questions
How many questions are in the BCHCT 131 guess paper and how many are shown here?
The file holds 12 solved questions across 16 pages. Five of those twelve are printed in full on this page with complete answers, which leaves seven questions available only in the paid file. The seven withheld questions are listed by topic and block on this page, so you know exactly what you are receiving before ordering anything from us.
Which sessions is the BCHCT 131 guess paper prepared for?
It targets the June 2026 and December 2026 term end examinations. The question selection is based on five consecutive papers running from December 2023 through to December 2025, including the most recent December 2025 sitting. Because both 2026 sessions draw on the same syllabus and the same paper pattern, one file covers both attempts without any change.
Is this BCHCT 131 guess paper useful for BSCM and BSCBCH students too?
Yes. BCHCT 131 is a discipline specific core course shared by Bachelor of Science (BSCG), Bachelor of Science (BSCM) under FYUP and Bachelor of Science Honours Biochemistry (BSCBCH). All three programmes follow the same four block syllabus of 19 units and sit the same two hour term end paper, so the file needs no modification for any of them. Students from all three programmes order the same PDF from us each session.
Does the BCHCT 131 guess paper guarantee the same questions in the exam?
No, and we will not claim that. It is a probability tool built on counted frequency across five past papers, not a leaked paper. It concentrates your revision on topics that have recurred most, which is a large advantage in a two hour exam. Final coverage of the whole syllabus remains your responsibility alongside the official block material.
Are the BCHCT 131 answers written in English or Hindi?
The answers are written in English, with all chemical structures, mechanisms and numericals presented as diagrams and equations. IGNOU permits answers in either medium for this paper. Structures, arrow mechanisms and calculation steps carry across both languages unchanged, so Hindi medium students still find the file usable for the diagram heavy questions such as VSEPR shapes, Newman projections and molecular orbital diagrams.
Is there a practical file needed for BCHCT 131?
No. BCHCT 131 is a four credit theory course with no practical component and no record file to submit. The laboratory work is a separate two credit course, BCHCL 132, which has its own lab manual, practical record and separate examination. Students frequently confuse the two codes when searching, so check the code carefully before ordering.
What is the exam pattern for the BCHCT 131 term end paper?
The paper runs two hours for a maximum of 50 marks. It is divided into two parts of 25 marks each, written in two separate answer books, and you attempt any five questions of 5 marks in each part. Sub-part splits are typically three plus two. Write your enrolment number, course code and part title on both answer books.
How is the BCHCT 131 solved file delivered after I contact you?
Delivery is digital. Message 9899436384 on WhatsApp with the course code and the complete 16 page PDF is sent to you on the same chat. There is no account registration, no shipping and no waiting period. You can ask about specific topics before deciding, and we will confirm whether that topic appears in the file.
Disclaimer: Unnati Educations is an independent academic support platform and is not affiliated with, endorsed by or connected to IGNOU (Indira Gandhi National Open University) in any way. This guess paper is based on trend analysis of past IGNOU question papers and supplements, rather than replaces, the official IGNOU block wise study material.