BCHCT 133 key facts: June 2026
- Course code: BCHCT-133
- Subject: Chemical Energetics, Equilibria and Functional Group Organic Chemistry-I
- Programme: Bachelor of Science (General) (BSCG) and Bachelor of Science (Multidisciplinary) (BSCM); also listed for BSCBCH
- Blocks and units: 4 blocks, 19 units in 2 volumes
- Maximum marks: 50 (Part I 25 + Part II 25)
- Duration: 2 hours
- Questions in the June 2026 paper: 14 numbered questions (7 per part), 27 answerable parts including the Question 13 alternative; attempt any 5 per part
- Answer books: Part I and Part II are written in separate answer books
- Companion lab course: BCHCL-134
- Solved on this page: 2 parts (Q4(b) and Q9(a)); all 27 in the paid file
BCHCT 133 Solved Question Paper June 2026 gives you complete, exam-length answers to the official IGNOU term-end paper of Chemical Energetics, Equilibria and Functional Group Organic Chemistry-I, written for BSCG and BSCM learners. Our chemistry team answered all 27 parts, from the Cp and Cv numerical in Question 1 to the Friedel-Crafts mechanism in Question 11, with every step, unit and equation shown.
1. What the June 2026 Solved Paper Includes
BCHCT 133 is the IGNOU chemistry core course that joins physical chemistry (thermodynamics, chemical and ionic equilibrium) with the organic chemistry of aromatic compounds, halides and oxygen-containing groups.
The June 2026 paper tests both halves in one sitting. Part I sets seven energetics and equilibria questions, six of them ending in a 3-mark numerical such as bond enthalpy, Kirchhoff's equation or a salt's H+ concentration. Part II sets seven organic questions built on mechanisms, name reactions and reaction completion.
Every part is answered in the full file, including both options of Question 13, so you can check your own attempt or revise exactly what IGNOU chose this session. The answers follow the four official blocks, which you can read on the official BCHCT-133 course page on eGyanKosh.
2. Two Answers Solved in Full, Twenty-Five Held Back
This page solves 2 of the 27 parts in full, Question 4(b) from Part I and Question 9(a) from Part II; the other 25 are listed below exactly as printed and answered only in the full file.
pH of an acetic acid and sodium acetate buffer
Question 4 (b): Calculate the pH of a buffer solution containing 0.15 mole of CH3COOH and 0.1 mole of CH3COONa per litre. Given: pKa (CH3COOH) = 4.745, log 2 = 0.3, log 3 = 0.48. (3)
A mixture of a weak acid and its salt with a strong base is an acidic buffer, so its pH is found with the Henderson-Hasselbalch equation.
Basis of the formula. For CH3COOH ⇌ H+ + CH3COO−, Ka = [H+][CH3COO−] ÷ [CH3COOH]. Taking negative logarithms gives pH = pKa + log ([salt] ÷ [acid]). Acetic acid is weakly ionised, and the acetate ions from the salt push its ionisation back further (common ion effect), so [CH3COOH] ≈ 0.15 M. Sodium acetate ionises completely, so [CH3COO−] ≈ 0.1 M.
Given: [acid] = 0.15 mol L−1, [salt] = 0.1 mol L−1, pKa = 4.745, log 2 = 0.3, log 3 = 0.48.
pH = pKa + log ([CH3COO−] ÷ [CH3COOH])
pH = 4.745 + log (0.1 ÷ 0.15)
pH = 4.745 + log (2 ÷ 3)
pH = 4.745 + (log 2 − log 3)
pH = 4.745 + (0.30 − 0.48)
pH = 4.745 − 0.18 = 4.565
Quick check. The solution holds more acid than salt, so the ratio [salt] ÷ [acid] is below 1 and its logarithm is negative. The pH must therefore sit a little below the pKa of 4.745, and 4.565 does.
Answer. The pH of the buffer is 4.565, or about 4.57.
Why t-butyl chloride follows SN1 and n-propyl bromide follows SN2
Question 9 (a): Explain why t-butyl chloride and n-propyl bromide undergo nucleophilic substitution reaction by SN1 and by SN2 mechanism, respectively. (4)
Whether an alkyl halide reacts by SN1 or SN2 depends mainly on the carbon that carries the halogen: how stable a carbocation it can give, and how crowded it is for a nucleophile coming in from the back.
t-Butyl chloride, (CH3)3C-Cl, reacts by SN1
- Stable carbocation: it is a tertiary halide, and ionisation gives the tert-butyl cation, (CH3)3C+. Three methyl groups stabilise it by their +I effect and by hyperconjugation with nine C-H bonds.
- Steric hindrance: the three bulky methyl groups block backside attack, so the one-step SN2 route is practically closed.
- Relief of strain: on ionisation the carbon changes from crowded sp3 (about 109.5°) to planar sp2 (120°), which favours the first step.
Step 1 (slow): (CH3)3C-Cl ⇌ (CH3)3C+ + Cl−
Step 2 (fast): (CH3)3C+ + H2O → (CH3)3C-OH2+ → (CH3)3C-OH + H+
Rate = k [(CH3)3CCl]
Only the halide appears in the rate law, so the reaction is first order. Polar protic solvents such as water help by solvating both ions. The planar carbocation can be attacked from either face, so a chiral substrate of this type would give a racemic product.
n-Propyl bromide, CH3CH2CH2-Br, reacts by SN2
- No stable carbocation: it is a primary halide, and the n-propyl cation would be too unstable to form, so SN1 is not a practical path.
- Open backside: the carbon bonded to Br carries two small hydrogen atoms, so the nucleophile can reach it easily from the side opposite to Br.
- Good leaving group: Br− leaves readily, which suits a single concerted step.
HO− + CH3CH2CH2-Br → [HO···CH2(C2H5)···Br]− → HO-CH2CH2CH3 + Br−
Rate = k [CH3CH2CH2Br] [OH−]
Bond making and bond breaking happen together through one five-coordinate transition state, so the reaction is second order and goes with inversion of configuration (Walden inversion). Strong nucleophiles and polar aprotic solvents such as acetone or DMSO favour it.
| Feature | t-Butyl chloride (SN1) | n-Propyl bromide (SN2) |
|---|---|---|
| Type of halide | Tertiary | Primary |
| Steps | Two, through a carbocation | One, concerted |
| Rate law | Rate = k [RX], first order | Rate = k [RX] [Nu−], second order |
| Stereochemistry | Racemisation | Inversion of configuration |
| Favoured by | Weak nucleophile, polar protic solvent | Strong nucleophile, polar aprotic solvent |
Conclusion. The stable tertiary carbocation and heavy crowding push t-butyl chloride to SN1, while the unstable primary cation and open backside push n-propyl bromide to SN2.
3. Questions Answered Only in the Full File
These 25 parts are printed as they appear in the June 2026 paper, with IGNOU's own numbering and marks. Reagents written over an arrow are shown in square brackets. Their answers, calculations and mechanisms are only in the paid file.
Part I: Chemical Energetics and Equilibria
Question 1 (a): Differentiate between a closed and an isolated thermodynamic system with the help of examples. (2)
Question 1 (b): Calculate the amount of heat required to increase the temperature of 2.00 moles of krypton from 100 K to 400 K in (i) an isobaric process and (ii) an isochoric process. Given: Cv,m = 12.5 J K−1 mol−1 and Cp,m = 20.8 J K−1 mol−1. (3)
Question 2 (a): State the zeroth law of thermodynamics and give the requirement for establishing thermal equilibrium. (2)
Question 2 (b): Determine the enthalpy change for CH4(g) + Cl2(g) → CH3Cl(g) + HCl(g). Given: bond enthalpies for C-H, C-Cl, Cl-Cl and H-Cl are 412, 338, 242 and 431 kJ mol−1 respectively. (3)
Question 3 (a): Give any two statements of the second law of thermodynamics. (2)
Question 3 (b): The standard enthalpy of formation of NO2(g) is −33.2 kJ mol−1 at 298 K. Calculate the enthalpy of formation of NO2 at 100 °C. Given: Cp values (J K−1 mol−1) are O2(g) = 29.3, NO2(g) = 37.2, N2(g) = 29.1. Assume the heat capacity values to be temperature independent in this range. (3)
Question 4 (a): What are buffer solutions? Give an example each of acidic and basic buffer solutions. (2)
Question 5 (a): When will ΔG° be equal to zero for an equilibrium reaction? (2)
Question 5 (b): An equilibrium mixture of three ideal gases A, B and C is obtained by the dissociation of gas A to the extent of 20% at a total pressure of 1.0 bar. The equilibrium is A(g) ⇌ B(g) + C(g). Calculate the value of Kp. (3)
Question 6 (a): Elemental sulphur undergoes a phase transition from the orthorhombic to the monoclinic form at 363 K. If the molar enthalpy of transition is −402 J mol−1, calculate the entropy of transition. (2)
Question 6 (b): How would the degree of ionisation of a weak acid change with the dilution of its solution? Explain. (3)
Question 7 (a): The sulphides of group IV cations are not precipitated in group II. Explain. (2)
Question 7 (b): Calculate the H+ concentration of 0.05 M sodium acetate solution, if the Ka of acetic acid is 1.80 × 10−5. (3)
Part II: Functional Group Organic Chemistry-I
Question 8 (a): What are vicinal dihalides? Give the structure and IUPAC name of one such dihalide. (2)
Question 8 (b): How is benzene obtained from (i) acetylene and (ii) sodium benzoate? (2)
Question 8 (c): What are nucleophiles? Write the structure of any two. (1)
Question 9 (b): Give two examples of m-directing groups in electrophilic aromatic substitution. (1)
Question 10: Write one reaction representing any five of the following name reactions. (5)
(i) Cannizzaro reaction (ii) Gattermann-Koch reaction (iii) Rosenmund reduction (iv) Linear polymerisation reaction (v) Sulphonation reaction (vi) Williamson ether synthesis
Question 11 (a): How is benzene converted to isopropyl benzene? Give the mechanism of the reaction in detail. (4)
Question 11 (b): Write the structure of phenolphthalein in alkaline medium. (1)
Question 12: Complete any five of the following reactions. (5)
(i) C2H5Cl + Na → [ether]
(ii) RCOR → [(i) RMgCl, (ii) H2O]
(iii) C6H5NH2 → [NaNO2 + HCl, 0 to 5 °C]
(iv) C6H5NO2 → [Δ, conc. HNO3, conc. H2SO4]
(v) RMgCl → [CO2, H2O]
(vi) HCHO → [Δ, conc. NaOH]
Question 13: Arrange the following in order of increasing acidity and explain your answer. (3 + 2)
(i) CH3OH (ii) C6H5OH (iii) p-NO2-C6H4-OH
Question 13 (Or): Give one example each of an E1 and an E2 reaction. Explain your answer. (5)
Question 14 (a): Why are certain organic compounds aromatic in nature? Give four structural features common to all aromatic compounds. (3)
Question 14 (b): Give one example each of (i) a benzenoid and (ii) a non-benzenoid aromatic compound. (2)
4. Two-Part Paper Pattern and Marks
The June 2026 paper carries 50 marks in 2 hours, split into two 25-mark parts; in each part you attempt any five of seven questions worth 5 marks each.
IGNOU asks you to write Part I and Part II in two separate answer books, each with your enrolment number, course code and part title. Mixing the two parts in one book is a common and avoidable slip.
| Question | Part | What it asks | Marks | Units |
|---|---|---|---|---|
| Q1 | I | Types of system; heat for krypton in two processes | 2 + 3 | 1, 2 |
| Q2 | I | Zeroth law; enthalpy change from bond enthalpies | 2 + 3 | 1, 3 |
| Q3 | I | Second law statements; formation enthalpy of NO2 at 100 °C | 2 + 3 | 3, 4 |
| Q4 | I | Buffer definition; pH of an acetate buffer | 2 + 3 | 8 |
| Q5 | I | Condition for ΔG° = 0; Kp from dissociation of A | 2 + 3 | 5, 6 |
| Q6 | I | Entropy of sulphur transition; ionisation on dilution | 2 + 3 | 4, 7 |
| Q7 | I | Group IV sulphides; H+ in sodium acetate | 2 + 3 | 9 |
| Q8 | II | Vicinal dihalides; benzene preparations; nucleophiles | 2 + 2 + 1 | 10, 13 |
| Q9 | II | SN1 versus SN2; m-directing groups | 4 + 1 | 12, 13 |
| Q10 | II | Name reactions, any five of six | 5 × 1 | 11, 17, 18, 19 |
| Q11 | II | Benzene to isopropyl benzene; phenolphthalein in alkali | 4 + 1 | 11, 16 |
| Q12 | II | Complete reactions, any five of six | 5 × 1 | 11, 13, 14, 18 |
| Q13 | II | Acidity order, or E1 and E2 examples | 3 + 2, or 5 | 13, 15, 16 |
| Q14 | II | Aromatic character; benzenoid and non-benzenoid examples | 3 + 2 | 10 |
The two-part format is the same in every official paper we checked from June 2023 to June 2026, and Part II often sets whole 5-mark questions, such as Questions 10 and 12 this session, where you pick five of six items.
Our IGNOU Previous Year Question Paper section groups past papers by course code so you can compare sessions quickly.
5. Syllabus by Block and Unit
BCHCT-133 has 4 blocks and 19 units in two volumes, and the June 2026 paper touches all 19 units at least once. The last column shows which June 2026 parts draw on each unit.
| Block | Unit | Core topics | June 2026 parts |
|---|---|---|---|
| Block 1: Chemical Energetics | Unit 1: Chemical Energetics: Basic Aspects | System, surroundings and boundary; intensive and extensive variables; zeroth law and temperature | Q1(a), Q2(a) |
| Block 1: Chemical Energetics | Unit 2: The First Law of Thermodynamics | Internal energy, work and heat; Cp and Cv of ideal gases; isothermal and adiabatic changes | Q1(b) |
| Block 1: Chemical Energetics | Unit 3: Thermochemistry | Hess's law; bond enthalpies; variation of enthalpy with temperature (Kirchhoff) | Q2(b), Q3(b) |
| Block 1: Chemical Energetics | Unit 4: Second and Third Laws of Thermodynamics | Kelvin-Planck and Clausius statements; entropy of phase transitions; Gibbs energy and spontaneity | Q3(a), Q6(a) |
| Block 2: Chemical and Ionic Equilibrium | Unit 5: Chemical Equilibrium-I | Reversible reactions; Gibbs energy change and the equilibrium constant; reaction quotient | Q5(a) |
| Block 2: Chemical and Ionic Equilibrium | Unit 6: Chemical Equilibrium-II | Kp and Kc and their relation; degree of dissociation; Le Chatelier's principle | Q5(b) |
| Block 2: Chemical and Ionic Equilibrium | Unit 7: Ionic Equilibrium-I | Strong and weak electrolytes; Ostwald's dilution law; factors affecting ionisation | Q6(b) |
| Block 2: Chemical and Ionic Equilibrium | Unit 8: Ionic Equilibrium-II | pH scale; ionisation of weak acids and bases; buffer solutions and the Henderson equation | Q4(a), Q4(b) (Sample 1) |
| Block 2: Chemical and Ionic Equilibrium | Unit 9: Ionic Equilibrium-III | Salt hydrolysis; solubility product; common ion effect in qualitative analysis | Q7(a), Q7(b) |
| Block 3: Aromatic Hydrocarbons and Halogen Derivatives | Unit 10: Preparation of Aromatic Hydrocarbons | Aromaticity and Hückel's rule; benzene from acetylene and from sodium benzoate; benzenoid and non-benzenoid rings | Q8(b), Q14(a), Q14(b) |
| Block 3: Aromatic Hydrocarbons and Halogen Derivatives | Unit 11: Reactions of Aromatic Compounds-I | Electrophilic substitution mechanism; nitration and sulphonation; Friedel-Crafts alkylation and acylation | Q10, Q11(a), Q12 |
| Block 3: Aromatic Hydrocarbons and Halogen Derivatives | Unit 12: Reactions of Aromatic Compounds-II | Activating and deactivating groups; ortho, para and meta direction; reactivity order | Q9(b) |
| Block 3: Aromatic Hydrocarbons and Halogen Derivatives | Unit 13: Alkyl Halides | Classification and naming; SN1 and SN2 mechanisms; E1, E2 and the Wurtz reaction | Q8(a), Q8(c), Q9(a) (Sample 2), Q12, Q13 (Or) |
| Block 3: Aromatic Hydrocarbons and Halogen Derivatives | Unit 14: Aryl Halides | Preparation through diazonium salts; low reactivity of the C-X bond; nucleophilic aromatic substitution | Q12 |
| Block 4: Oxygen Containing Organic Compounds | Unit 15: Alcohols | Classification of alcohols; acidity of alcohols; dehydration to alkenes | Q13 |
| Block 4: Oxygen Containing Organic Compounds | Unit 16: Phenols | Acidity and substituent effects; phenolphthalein preparation; electrophilic reactions of phenol | Q11(b), Q13 |
| Block 4: Oxygen Containing Organic Compounds | Unit 17: Ethers | Williamson synthesis; cleavage by HI; crown ethers | Q10 |
| Block 4: Oxygen Containing Organic Compounds | Unit 18: Aldehydes and Ketones | Nucleophilic addition; Grignard additions; Cannizzaro and aldol reactions | Q10, Q12 |
| Block 4: Oxygen Containing Organic Compounds | Unit 19: Aromatic Aldehydes and Ketones | Gattermann-Koch formylation; Rosenmund reduction; benzoin and Perkin reactions | Q10 |
Block 2 alone supplies seven of the fourteen Part I parts, so the ionic equilibrium units deserve the most numerical practice. For a slower walk through all 19 units in simple English, our BCHCT 133 Study Material follows the same block order.
6. Topics IGNOU Keeps Repeating
In the five official papers we checked (June 2023, June 2024, December 2024, December 2025 and June 2026), 8 topic groups appeared every single time, from enthalpy calculations to diazonium salts.
| Topic group | Jun 2023 | Jun 2024 | Dec 2024 | Dec 2025 | Jun 2026 | Papers (of 5) |
|---|---|---|---|---|---|---|
| Thermodynamic terms: systems, intensive variables, state functions | Q1(a) | Q1(a) | Q1(a) | Q1(a) | Q1(a), Q2(a) | 5 |
| Enthalpy of reaction from given data | Q2(b) | Q2(b) | Q2(b) | Q2(b) | Q2(b) | 5 |
| Spontaneity, entropy and the second law | Q3(a), Q3(b) | Q2(a), Q3(a) | Q4(a) | Q3(a) | Q3(a) | 5 |
| Kp and Kc expressions and equilibrium calculations | Q4(a), Q5(b) | Q4(a), Q4(b) | Q3(b) | Q4(a), Q4(b) | Q5(b) | 5 |
| Aromaticity, Hückel's rule and why benzene substitutes | Q8(b) | Q10(a) | Q8(a) | Q8(b) | Q14(a), Q14(b) | 5 |
| Nucleophilic substitution: SN1 and SN2 | Q12(a) | Q9(a) | Q8(b) | Q14(ii) | Q9(a) (Sample 2) | 5 |
| Friedel-Crafts alkylation and acylation | Q11(iii) | Q8(a)(i), Q10(b) | Q9(a)(ii) | Q11 | Q11(a) | 5 |
| Diazonium salts and their reactions | Q8(a)(iii) | Q8(a)(iii) | Q9(a)(iii) | Q10(i) | Q12(iii) | 5 |
| Entropy of fusion or phase transition | — | Q3(b) | Q4(b) | Q5(b) | Q6(a) | 4 |
| Buffer solutions: definition and pH | Q6(a) | Q6(a) | Q6(b) | — | Q4(a), Q4(b) (Sample 1) | 4 |
| Weak acid ionisation, degree of ionisation and dilution | Q4(b), Q6(b) | Q6(b) | Q6(a) | — | Q6(b) | 4 |
| Salt hydrolysis and pH of salt solutions | Q7(a) | Q7(a), Q7(b) | — | Q6(b) | Q7(b) | 4 |
| Common ion effect and solubility product | Q7(b) | — | Q7(a), Q7(b) | Q7(a), Q7(b) | Q7(a) | 4 |
| Elimination: E1, E2 and Saytzeff's rule | Q10(b) | Q12(iii) | — | Q9(a) | Q13 (Or) | 4 |
| Directing and activating groups | Q14(ii) | — | Q12(a) | Q9(b) | Q9(b) | 4 |
| Acidity of phenols | Q9(a) | — | Q14(a) | Q13(vi) | Q13 | 4 |
| Nitration and sulphonation of benzene | Q14(i) | Q14(a) | — | Q13(ii) | Q10(v), Q12(iv) | 4 |
| Crown ethers | Q14(iii) | Q12(ii) | Q11(a) | Q13(iv) | — | 4 |
| When ΔG° equals zero | Q5(a) | — | Q5(a) | — | Q5(a) | 3 |
| Heat capacity and heat required | Q1(b) | — | Q1(b) | — | Q1(b) | 3 |
| Rosenmund reduction | Q11(v) | — | — | Q10(iii) | Q10(iii) | 3 |
| Williamson ether synthesis | Q10(a)(iii) | — | — | Q12(iii) | Q10(vi) | 3 |
| Phenolphthalein structure and indicator action | — | — | Q13(b) | Q14(i) | Q11(b) | 3 |
| Aldol and Cannizzaro reactions | — | Q12(i) | — | Q12(v), Q14(iii) | Q10(i), Q12(vi) | 3 |
| Enthalpy at another temperature (Kirchhoff) | — | — | — | Q3(b) | Q3(b) | 2 |
| Le Chatelier's principle | — | Q5(a), Q5(b) | Q5(b) | — | — | 2 |
| Grignard reagent reactions | — | — | Q12(b) | — | Q12(ii), Q12(v) | 2 |
Some questions return almost word for word. The ΔG° question in June 2026 appeared in June 2023 and December 2024, and the A ⇌ B + C dissociation at 20% was set in June 2024 before returning this session with Kp asked instead of partial pressures.
Crown ethers came up in all four earlier papers we checked and then skipped June 2026, so it is a strong candidate for the next exam. The count covers only papers we could open on IGNOU's own servers; December 2023 and June 2025 were not available there.
For predicted questions across more courses, our IGNOU Solved Guess Paper page lists BCHCT-133 alongside the other BSCG chemistry codes.
7. Practical Links with the BCHCL-134 Lab
BCHCT-133 is a theory course; its practical work sits in the companion lab course BCHCL-134, which covers thermochemistry, pH measurement and basic organic techniques that feed straight into this paper.
| Lab area | Practical work | June 2026 parts it supports |
|---|---|---|
| Thermochemistry | Enthalpy of neutralisation of a strong acid by a strong base | Q2(b), Q3(b): enthalpy changes and how they are measured |
| Thermochemistry | Enthalpy of solution and of hydration of a salt | Q1(b), Q3(b): heat absorbed and heat capacity |
| Thermochemistry | Enthalpy of ionisation of a weak acid | Q6(b): ionisation of weak acids |
| pH measurements | pH of acid, base and salt solutions with a pH meter | Q7(b): pH and H+ of a salt solution |
| pH measurements | Preparing buffers and checking their pH | Q4(a), Q4(b): acetate buffer |
| Organic techniques | Heating, cooling, stirring and filtration; crystallisation and distillation | Q8(b), Q14: handling and purifying aromatic compounds |
| Organic preparations | Preparation of simple organic compounds | Q10, Q12: name reactions and conversions |
The lab areas above are matched to this paper from IGNOU's own course description; check your BCHCL-134 manual for the exact experiment numbers and titles. Measuring a buffer's pH on a real pH meter makes the Question 4 numerical far easier to trust, because you have seen the value move yourself. We also prepare the complete BCHCL-134 record file with aim, apparatus, procedure, observations and result; ask for it on the same WhatsApp number.
8. How Our Answers Are Written and Checked
Each answer is written by our chemistry subject team from the official BCHCT-133 blocks, checked against earlier IGNOU papers and reviewed before release.
We start from the exact wording of the June 2026 paper. A 3-mark numerical shows the formula, given data, substitution, units and a check on whether the result makes sense. A 4 or 5-mark organic answer gives the reaction, the mechanism with each intermediate, and the reason behind each step.
The file also flags where the printed data look unusual, so you are not thrown in the exam hall. Where a given sign differs from standard textbook values, the answer solves the question as set and adds a short note.
9. Solved File Index
The full file answers all 27 parts of the June 2026 paper: 2 are on this page and 25 are in the paid file only.
| Part | Section | Topic | Marks | Unit | Where the answer is |
|---|---|---|---|---|---|
| Q1(a) | I | Closed versus isolated systems | 2 | Unit 1 | Full file |
| Q1(b) | I | Heat at constant pressure and volume | 3 | Unit 2 | Full file |
| Q2(a) | I | Zeroth law | 2 | Unit 1 | Full file |
| Q2(b) | I | Enthalpy from bond enthalpies | 3 | Unit 3 | Full file |
| Q3(a) | I | Second law statements | 2 | Unit 4 | Full file |
| Q3(b) | I | Enthalpy at 100 °C (Kirchhoff) | 3 | Unit 3 | Full file |
| Q4(a) | I | Buffer definition and examples | 2 | Unit 8 | Full file |
| Q4(b) | I | pH of an acetate buffer | 3 | Unit 8 | Sample 1 above |
| Q5(a) | I | When ΔG° is zero | 2 | Unit 5 | Full file |
| Q5(b) | I | Kp from 20% dissociation | 3 | Unit 6 | Full file |
| Q6(a) | I | Entropy of sulphur transition | 2 | Unit 4 | Full file |
| Q6(b) | I | Degree of ionisation on dilution | 3 | Unit 7 | Full file |
| Q7(a) | I | Group IV sulphides in group II | 2 | Unit 9 | Full file |
| Q7(b) | I | H+ in sodium acetate solution | 3 | Unit 9 | Full file |
| Q8(a) | II | Vicinal dihalides | 2 | Unit 13 | Full file |
| Q8(b) | II | Benzene from acetylene and sodium benzoate | 2 | Unit 10 | Full file |
| Q8(c) | II | Nucleophiles | 1 | Unit 13 | Full file |
| Q9(a) | II | SN1 versus SN2 | 4 | Unit 13 | Sample 2 above |
| Q9(b) | II | m-directing groups | 1 | Unit 12 | Full file |
| Q10 | II | Six name reactions, any five | 5 | Units 11, 17, 18, 19 | Full file |
| Q11(a) | II | Benzene to isopropyl benzene | 4 | Unit 11 | Full file |
| Q11(b) | II | Phenolphthalein in alkali | 1 | Unit 16 | Full file |
| Q12 | II | Six reactions to complete, any five | 5 | Units 11, 13, 14, 18 | Full file |
| Q13 | II | Acidity order of three hydroxy compounds | 3 + 2 | Units 15, 16 | Full file |
| Q13 (Or) | II | E1 and E2 examples | 5 | Unit 13 | Full file |
| Q14(a) | II | Aromatic character and its features | 3 | Unit 10 | Full file |
| Q14(b) | II | Benzenoid and non-benzenoid examples | 2 | Unit 10 | Full file |
Writing other science papers this term? Our BSCG Question Paper collection covers the other chemistry, botany and zoology codes session by session, so you can plan every paper together.
10. Programmes That Include BCHCT 133
BCHCT 133 is printed for the IGNOU BSCG and BSCM, and it is also listed for the B.Sc. (Honours) Biochemistry (BSCBCH), with the same code and the same term-end paper.
In the Bachelor of Science (General), BCHCT-133 follows BCHCT-131 Atomic Structure, Bonding, General Organic Chemistry and Aliphatic Hydrocarbons. The electronic effects and carbocation ideas from BCHCT-131 are exactly what Question 9(a) and Question 13 build on.
The Bachelor of Science (Multidisciplinary), BSCM, runs under IGNOU's four-year structure, and the June 2026 paper header names it beside BSCG. BSCBCH learners take the course as their chemistry foundation for biochemistry, so one solved file works across all three; check your programme guide to confirm your semester.
11. How to Get the Full Solved Question Paper
Send "BCHCT-133 June 2026" on WhatsApp to 9899436384, and the full file with all 27 answered parts is shared on the same chat after payment.
- Message 9899436384 with the course code and your programme: BSCG, BSCM or BSCBCH.
- Our IGNOU desk replies with the price and payment options.
- Receive the PDF with all 27 parts, including the 25 not shown here.
- Message the same number with any doubt while you revise.
12. BCHCT 133 June 2026 FAQs
How many answers are in the full solved file, and how do I get it on WhatsApp?
The full file answers all 27 parts of the June 2026 paper: 14 parts from Part I on energetics and equilibria and 13 from Part II on organic chemistry, including the Question 13 alternative. This page shows 2 of them, so 25 are only in the file. Send BCHCT-133 June 2026 on WhatsApp to 9899436384, and our IGNOU desk replies with the price and shares the PDF on the same chat.
Which answers are solved in full on this page?
Two answers are shown in full. From Part I, Question 4(b) works out the pH of an acetic acid and sodium acetate buffer with the Henderson-Hasselbalch equation. From Part II, Question 9(a) explains why t-butyl chloride follows SN1 while n-propyl bromide follows SN2. Together they show how the file handles a numerical and a mechanism answer, the two answer styles this paper uses most.
What is the exam pattern of the June 2026 paper?
The June 2026 BCHCT-133 paper carries 50 marks for 2 hours and is split into two parts of 25 marks, each written in a separate answer book. Part I on chemical energetics and equilibria offers Questions 1 to 7, and Part II on functional group organic chemistry offers Questions 8 to 14. In each part you attempt any five questions of 5 marks each.
Which BCHCT 133 topics repeat most in IGNOU term-end papers?
Across the five official papers we checked, June 2023 to June 2026, several topics appeared every time: enthalpy of reaction from given data, spontaneity and entropy, equilibrium constant calculations, aromaticity, nucleophilic substitution, Friedel-Crafts reactions and diazonium salts. The question on when ΔG° equals zero appeared in June 2023, December 2024 and June 2026. Treat these as revision priorities, not a promise.
Does BCHCT 133 have a practical file or a lab course?
BCHCT-133 itself is a theory course with a 2-hour written paper. Its lab partner is BCHCL-134, which covers thermochemistry experiments such as enthalpies of solution and neutralisation, pH measurement with a pH meter, and organic techniques like crystallisation, distillation and simple preparations. We also prepare the BCHCL-134 record file, and you can ask for it on the same WhatsApp number.
Which IGNOU programmes include BCHCT 133?
BCHCT-133 is a chemistry core course of the IGNOU School of Sciences. The June 2026 paper is printed for the Bachelor of Science (General), BSCG, and the Bachelor of Science (Multidisciplinary), BSCM, under the four-year structure. It is also listed for the B.Sc. (Honours) Biochemistry, BSCBCH. Learners in these programmes write the same term-end paper, so one solved file serves each.
Are these official IGNOU answers?
No. IGNOU publishes question papers, not model answers. Our chemistry subject team wrote every answer after studying the official BCHCT-133 blocks and earlier term-end papers, and Academic Head Sheetal Kirola reviewed them. Unnati Educations is an independent study-support platform and is not affiliated with IGNOU, so use the file as a revision guide alongside your official course material.
How long should an answer be for 3, 4 and 5 mark questions?
The paper sets no word limit, but time does. You write ten 5-mark questions in 120 minutes, so each deserves about 10 to 12 minutes. A 3-mark numerical needs the formula, substituted values, units and a one-line conclusion, roughly 120 to 180 words. A 4 or 5-mark mechanism needs about 250 to 350 words with equations, like the two samples on this page.
13. Who Wrote and Checked the BCHCT 133 Answers
The BCHCT 133 answers were written by the Unnati Educations chemistry team and reviewed by Sheetal Kirola.
Prateek Talwar, a Company Secretary who founded Unnati Educations to support IGNOU and NIOS learners, publishes the IGNOU solved-paper series. Sheetal Kirola, Academic Head (M.Ed.), reviews every IGNOU file we release and checks units, signs, reagents and mechanism steps against the BCHCT-133 blocks.