BCHCT 137 key facts: June 2026
- Course code: BCHCT 137 (printed BCHCT-137)
- Subject: Coordination Chemistry, States of Matter and Chemical Kinetics
- Programme: Bachelor of Science (General), BSCG, and Bachelor of Science (Multidisciplinary), BSCM
- Credits: 4 theory, taken with the 2-credit lab course BCHCL 138
- Blocks and units: 4 blocks, 14 units
- Maximum marks: 50 (Section A 25 + Section B 25)
- Duration: 2 hours
- Questions in the paper: 14 (7 per section, attempt any 5 from each, 4 internal "or" choices); printed code D-4301
- Answer sheets: Section A and Section B are written on separate sheets
- Samples shown here: 2 (Q1 and Q2); all 14 in the paid file, including every "or" option
BCHCT 137 Solved Question Paper for June 2026 gives B.Sc. students the official IGNOU term-end questions of Coordination Chemistry, States of Matter and Chemical Kinetics with complete answers written by our chemistry team. Two answers are open on this page as proof of quality, and the full file with all 14 answers is available on WhatsApp 9899436384.
1. What the June 2026 Solved Paper Covers
BCHCT 137 is a 4-credit core chemistry course in IGNOU's Bachelor of Science (General) programme, also studied in Bachelor of Science (Multidisciplinary).
The course runs across two volumes. Volume I deals with d-block and f-block elements and the chemistry of complexes, from Werner's theory to crystal field splitting. Volume II moves to physical chemistry: gases, liquids and solids, then rates of reaction. The June 2026 paper follows exactly that split, with Section A on coordination chemistry and Section B on states of matter and kinetics.
Our solved file takes that paper question by question. Short-answer parts such as the softness of zinc and cadmium get crisp 2½-mark answers, while 5-mark items like the Fe3+ spin-state numerical, the van der Waals critical constant derivation and the collision theory comparison get full working, labelled figures and a clean final line an examiner can tick.
What makes this paper tricky is the mix. In one sitting you switch from naming [Pt(py)4][PbF4] to deriving the kinetic gas equation to finding the unit of k for a third-order rate law. The file keeps each answer in the style its topic demands, so inorganic answers read like inorganic answers and derivations read like derivations.
2. Two Answers Solved in Full, Twelve Held Back
Q1 and Q2 from Section A of the June 2026 paper are solved in full below; the remaining 12 questions are answered only in the full file.
The question text is reproduced exactly as printed in the official paper. Q1 asks you to attempt any two parts, but we have answered all three so you can choose the two you are most confident writing.
Colour of titanium compounds, softness of Zn and Cd, and chromium in chromate
Question 1: Attempt any two parts. (2 × 2½ = 5)
(a) Which of these is coloured and why: TiCl3 or TiO2?
(b) Why are Zn and Cd soft?
(c) What is the oxidation state of Cr in CrO42−? Is it oxidising or reducing, and why?
(a) TiCl3 is coloured, TiO2 is not
In TiCl3, titanium is in the +3 oxidation state, so the Ti3+ ion has the configuration [Ar]3d1. In the octahedral field around the ion, this single d electron sits in a lower-energy t2g orbital and can jump to a higher-energy eg orbital by absorbing light from the visible region. The colour we see is the complementary colour of the light absorbed, so TiCl3 appears violet.
In TiO2, titanium is in the +4 state, giving Ti4+ the configuration [Ar]3d0. With no d electron at all, no d-d transition is possible, no visible light is absorbed and TiO2 is white. That is exactly why TiO2 is used as a white pigment in paints.
(b) Why zinc and cadmium are soft
Zinc and cadmium are soft because their d sub-shell is completely filled. Zn has the configuration [Ar]3d104s2 and Cd has [Kr]4d105s2. In most transition metals, unpaired (n−1)d electrons join the ns electrons in metallic bonding, and this extra bonding makes metals such as Cr, Fe and W hard with high melting points.
In Zn and Cd the full d10 set does not take part in metallic bonding, so only the two ns electrons hold the lattice together. The metallic bonds are therefore weak. As a result both metals are soft and have low melting points, about 420 °C for zinc and about 321 °C for cadmium, far below iron at about 1538 °C.
(c) Oxidation state of Cr in CrO42− and its nature
Let the oxidation state of Cr be x. Oxygen is −2 and the ion carries a charge of −2, so x + 4(−2) = −2, which gives x = +6. Chromium is in the +6 state in the chromate ion.
Chromate is an oxidising agent. Cr(VI) has the configuration 3d0 and +6 is the highest oxidation state chromium can reach, so it cannot lose more electrons; it can only gain them. In acidic solution chromate changes to dichromate, 2CrO42− + 2H+ ⇌ Cr2O72− + H2O, which is then reduced to the stable Cr3+ ion (t2g3).
The half-reaction is Cr2O72− + 14H+ + 6e− → 2Cr3+ + 7H2O, with E° = +1.33 V. The large positive electrode potential confirms that Cr(VI) readily accepts electrons, which is why acidified dichromate oxidises Fe2+ to Fe3+ in titrations.
Lanthanoids compared with actinoids, and lanthanoid contraction
Question 2: Compare the chemistry of the actinoids with that of the lanthanoids with respect to: (i) electronic configuration (ii) oxidation states. (5)
Or: What is lanthanoid contraction? Give an important consequence of this.
Lanthanoids and actinoids compared
Lanthanoids (cerium, Z = 58, to lutetium, Z = 71) and actinoids (thorium, Z = 90, to lawrencium, Z = 103) are both f-block series. The key difference is that the actinoid 5f orbitals behave very differently from the lanthanoid 4f orbitals, and that difference shows up in both configuration and oxidation states.
(i) Electronic configuration. Lanthanoids fill the 4f orbitals, with the general configuration [Xe]4f1–145d0–16s2. Actinoids fill the 5f orbitals, with the general configuration [Rn]5f1–146d0–17s2. The 4f orbitals lie deep inside the atom, well shielded by the filled 5s and 5p shells, so they hardly take part in bonding. The 5f orbitals extend further out and are less shielded.
Because the 5f, 6d and 7s levels are very close in energy, early actinoids show irregular configurations. Thorium is [Rn]6d27s2 with no 5f electron, protactinium is [Rn]5f26d17s2 and uranium is [Rn]5f36d17s2. In lanthanoids the 4f and 5d gap is larger, so most members simply add electrons to 4f, with a 5d1 electron seen mainly in Ce, Gd and Lu.
(ii) Oxidation states. Lanthanoids show +3 as their main and most stable oxidation state. A few also show +2 or +4 when that gives an empty, half-filled or full 4f shell: Eu2+ (4f7) and Yb2+ (4f14), Ce4+ (4f0) and Tb4+ (4f7). These states tend to return to +3, which is why Ce4+ acts as an oxidising agent and Eu2+ as a reducing agent.
Actinoids show a much wider range, from +3 up to +7, because electrons from 5f, 6d and 7s levels of similar energy can all be removed. Thorium is mostly +4, uranium shows +3 to +6 with +6 common, as in the uranyl ion UO22+, and neptunium and plutonium reach +7. From americium onwards the +3 state dominates, so the later actinoids start to resemble the lanthanoids.
| Feature | Lanthanoids | Actinoids |
|---|---|---|
| Orbitals being filled | 4f, deeply buried and well shielded | 5f, more exposed and able to join bonding |
| General configuration | [Xe]4f1–145d0–16s2 | [Rn]5f1–146d0–17s2 |
| Main oxidation state | +3 for every member | +4 for Th, +6 common for U, +3 from Am onwards |
| Range of oxidation states | +2 to +4 | +3 to +7 (Np and Pu reach +7) |
In short, actinoid chemistry is richer and more complicated than lanthanoid chemistry because 5f electrons are less shielded and sit close in energy to the 6d and 7s electrons.
Or: Lanthanoid contraction and its consequence
Lanthanoid contraction is the steady decrease in atomic and ionic radii across the series from lanthanum to lutetium. The radius of the M3+ ion falls from about 103 pm for La3+ to about 86 pm for Lu3+.
The cause is the poor shielding power of 4f electrons. With each step along the series the nuclear charge rises by one unit and one more electron enters the 4f level. Because f orbitals are diffuse, this added electron shields the outer electrons only weakly, so the effective nuclear charge keeps rising and pulls the whole electron cloud inward.
The most important consequence is that elements of the second and third transition series in the same group end up almost the same size. Zirconium (atomic radius about 160 pm) and hafnium (about 159 pm) are nearly identical, so their chemistry is so similar that they occur together in nature and are very hard to separate. The contraction also makes the hydroxides less basic from La(OH)3 to Lu(OH)3.
3. Questions Answered Only in the Full File
These 12 questions are listed exactly as printed. Their answers, diagrams and working are available only in the full solved file.
Section A (25 marks)
Question 3 (a): Determine the coordination number and oxidation state of the central metal ion in (i) [Fe(CN)6]3− (ii) [Cu(en)2]2+. (3)
Question 3 (b): Give the IUPAC names of any two of the following. (2)
(i) [Co(NH3)5(H2O)]Cl3 (ii) K3[Al(ox)3] (iii) [Pt(py)4][PbF4]Question 4 (a): Label any three of the following ligands as monodentate, bidentate, ambidentate or polydentate. (3)
(i) Water (ii) Thiosulphate ion (iii) 1,2-diaminoethane (en) (iv) EDTAQuestion 4 (b): Write the formulae of the following. (2)
(i) Potassium tetracyanidonickelate(II) (ii) μ-dihydroxidobis{tetraaquacobalt(III)} nitrate
Question 5 (a): [Ma2b2] (a and b are monodentate ligands) exhibits geometrical isomerism. What is the geometry of the complex? Draw the isomers. (3)
Question 5 (b): Indicate the isomerism shown in the following pairs. (2)
(i) [Pt(NH3)4Cl2]Br2 and [Pt(NH3)4Br2]Cl2
(ii) [Co(NH3)6][Cr(SCN)6] and [Cr(NH3)6][Co(SCN)6]Question 5 (Or): Name the metals present in haemoglobin and chlorophyll.
Question 6 (a): Using VBT, explain why [Co(NH3)6]3+ and [CoF6]3− differ in magnetic behaviour. (3)
Question 6 (b): Calculate the CFSE of an octahedral complex with three electrons in the d orbitals. (2)
Question 6 (Or): Why are octahedral complexes of copper(II) tetragonally distorted?
Question 7: The pairing energy P for the Fe3+ ion is 29,875 cm−1 and Δ0 for [Fe(H2O)6]3+ is 13,700 cm−1. Using this information find out: (5)
(i) whether the complex is high spin or low spin
(ii) the number of unpaired electrons
(iii) whether the complex is coloured or notQuestion 7 (Or): What would be the CFSE for an octahedral complex of a d7 ion in a weak field and a strong field? What is the relationship between Δt and Δ0?
Section B (25 marks)
Question 8 (a): Write down the basic assumptions of the kinetic theory of gases. (2)
Question 8 (b): Derive an expression for the pressure of a gas, assuming motion of the gas in a cubical container. (3)
Question 9: Define van der Waals isotherms. Derive expressions for Pc, Vc and Tc in terms of the van der Waals constants a and b. (2 + 3)
Question 10 (a): Explain hydrogen bonding with two suitable examples. (3)
Question 10 (b): Write four methods (names only) for the determination of surface tension. (2)
Question 11: What are amorphous and crystalline solids? Illustrate their properties in a figure or compare them in tabular form. (2 + 3)
Question 12 (a): Define Bragg's law. Give all the terms in the equation. (2)
Question 12 (b): Explain packing efficiency taking the example of the body centred cubic (bcc) lattice structure, with illustration. (3)
Question 13 (a): Define rate of reaction and draw a plot of the concentration of reactants and products against time. (2)
Question 13 (b): The experimentally determined rate law for 2NO + Cl2 → 2NOCl(g) is rate = k[NO]2[Cl2]. (3)
(i) What will be the order of reaction with respect to [Cl2]?
(ii) What is the overall order of reaction and the unit of k?Question 14: Explain the collision theory of bimolecular reactions. Write down its postulates. Compare collision theory with Arrhenius theory. (3 + 2)
4. Syllabus by Block and Unit
BCHCT 137 has 4 blocks and 14 units, and every one of the 14 units is tested somewhere in the June 2026 paper.
Blocks 1 and 2 feed Section A and Blocks 3 and 4 feed Section B, which is why the paper splits so neatly into inorganic and physical chemistry.
| Block | Unit | Key topics in the unit | June 2026 question |
|---|---|---|---|
| Block 1: d and f Block Elements | Unit 1: Transition Elements-I | Periodic trends in radii and ionisation energy; stability of oxidation states of Mn, Fe and Cu; Latimer diagrams | Q1(b), Q1(c) (Sample 1) |
| Block 1: d and f Block Elements | Unit 2: Transition Elements-II | Formation of complexes; origin of colour in transition metal compounds; magnetic and catalytic properties | Q1(a) (Sample 1) |
| Block 1: d and f Block Elements | Unit 3: Inner-Transition Elements | Lanthanoid contraction; oxidation states and colour of Ln ions; ion-exchange separation of lanthanoids | Q2 and its "or" choice (Sample 2) |
| Block 2: Coordination Chemistry | Unit 4: Coordination Chemistry-I | Werner's coordination theory; ligands and coordination number; IUPAC nomenclature of complexes | Q3, Q4 |
| Block 2: Coordination Chemistry | Unit 5: Coordination Chemistry-II | Structural and stereoisomerism for coordination numbers 4 and 6; valence bond theory applied to complexes of Cr, Fe, Co, Ni and Cu | Q5(a), Q5(b), Q6(a) |
| Block 2: Coordination Chemistry | Unit 6: Crystal Field Theory-I | Octahedral splitting and CFSE; weak and strong fields; spectrochemical series | Q6(b), Q7 |
| Block 2: Coordination Chemistry | Unit 7: Crystal Field Theory-II | Tetrahedral and square planar splitting; distortion of octahedral geometry; common applications of complexes | Q5 (Or), Q6 (Or), Q7 (Or) |
| Block 3: States of Matter | Unit 8: Kinetic Theory of Gases | Postulates and kinetic gas equation; Maxwell-Boltzmann distribution; mean free path | Q8(a), Q8(b) |
| Block 3: States of Matter | Unit 9: Real Gases and their Liquefaction | Compressibility factor; van der Waals equation; Andrews isotherms of CO2 and critical constants | Q9 |
| Block 3: States of Matter | Unit 10: Liquids | Structure of liquids; surface tension and its determination; coefficient of viscosity | Q10(a), Q10(b) |
| Block 3: States of Matter | Unit 11: Solids-I | Amorphous and crystalline solids; Bravais lattices and cubic geometry; Miller indices | Q11, Q12(b) |
| Block 3: States of Matter | Unit 12: Solids-II | X-ray diffraction and Bragg's law; NaCl, KCl and CsCl structures; crystal defects and liquid crystals | Q12(a) |
| Block 4: Chemical Kinetics | Unit 13: Chemical Kinetics-I | Rate of reaction and factors affecting it; order and molecularity; zero, first and second order integrated laws | Q13(a), Q13(b) |
| Block 4: Chemical Kinetics | Unit 14: Chemical Kinetics-II | Initial rate, half-life and isolation methods; collision and activated complex theories; Arrhenius comparison | Q14 |
If you are still reading the blocks themselves, keep our BCHCT 137 Study Material open alongside this table so each unit maps straight onto the question you will face.
5. Paper Pattern and Question Map
The June 2026 paper has 14 questions of 5 marks each, split 7 and 7 across two sections, and you answer 5 from each section for a total of 50 marks in 2 hours.
| Section | Area of the course | Questions set | Attempt | Marks |
|---|---|---|---|---|
| Section A | d and f block elements, coordination chemistry, crystal field theory | Q1 to Q7, with "or" choices in Q2, Q5, Q6 and Q7 | Any 5 | 25 |
| Section B | Gases, liquids, solids and chemical kinetics | Q8 to Q14, no "or" choices | Any 5 | 25 |
| Total | All 4 blocks | 14 questions | 10 answers on separate answer sheets | 50 |
Most questions are split into a 2 or 3 mark part and a 3 or 2 mark part, so a single slip rarely costs a full question. Section A rewards exact naming and electron counting, while Section B rewards neat derivations and correct units.
You can compare sessions through our IGNOU Previous Year Question Paper collection.
6. Topics That Keep Coming Back
In the three official BCHCT 137 papers we could read in full, 11 topics were asked every single time, and the June 2026 paper repeats several December 2023 questions almost word for word.
This grid is built only from official IGNOU papers on webservices.ignou.ac.in: June 2022, December 2023 and the June 2026 paper itself. The June 2023 paper is online only as a scanned image we could not read reliably, and we did not find official copies for December 2022, June 2024, December 2024, June 2025 or December 2025, so they are left out rather than guessed.
| Topic | Jun 2022 | Dec 2023 | Jun 2026 | Times asked (of 3) |
|---|---|---|---|---|
| Colour of transition metal ions (d0 against dn) | Yes | Yes | Yes (Sample 1) | 3 |
| Lanthanoids compared with actinoids | Yes | Yes | Yes (Sample 2) | 3 |
| Ligand types: ambidentate, bidentate, polydentate | Yes | Yes | Yes | 3 |
| Isomerism in coordination complexes | Yes | Yes | Yes | 3 |
| CFSE and crystal field effects in weak and strong fields | Yes | Yes | Yes | 3 |
| Kinetic theory of gases and the gas pressure equation | Yes | Yes | Yes | 3 |
| Van der Waals equation and critical constants | Yes | Yes | Yes | 3 |
| Liquids: viscosity and surface tension | Yes | Yes | Yes | 3 |
| Crystalline solids, lattices and crystal systems | Yes | Yes | Yes | 3 |
| Cubic unit cells and packing efficiency | Yes | Yes | Yes | 3 |
| Order of reaction, rate law and half-life | Yes | Yes | Yes | 3 |
| Softness of zinc and cadmium | — | Yes | Yes (Sample 1) | 2 |
| Lanthanoid contraction and its consequence | — | Yes | Yes (Sample 2) | 2 |
| Coordination number, oxidation state, IUPAC names and formulae | — | Yes | Yes | 2 |
| VBT hybridisation and magnetic behaviour | — | Yes | Yes | 2 |
| Spin state and unpaired electrons of Fe(III) complexes | — | Yes | Yes | 2 |
| Iron in bioinorganic chemistry | — | Yes | Yes | 2 |
| Collision and activated complex theories | — | Yes | Yes | 2 |
The overlap is striking. Zn and Cd softness, the [Pt(NH3)4Cl2]Br2 and [Pt(NH3)4Br2]Cl2 pair, the lanthanoid contraction "or" choice and the d7 CFSE question all appear in both December 2023 and June 2026. Hydrogen bonding and Bragg's law are the new entries this session.
Start revision with the three-times topics, then add the two-times ones. For a wider list across courses, see our IGNOU Solved Guess Paper page.
7. How Our Answers Are Written and Checked
Every BCHCT 137 answer is written by a chemistry-trained author, matched to the marks printed against the question and then checked line by line by a second reviewer before it goes into the file.
Each answer is checked against the official IGNOU course blocks on the eGyanKosh BCHCT-137 course page, so the terms, symbols and conventions match what your evaluator expects to see.
Length follows the mark weight. A 2½-mark part gets a direct answer of about 80 to 120 words, while a 5-mark question gets around 250 to 300 words or a full derivation. Numericals show the formula, substitution, calculation and unit on separate lines, and every configuration is written out in full.
Diagrams are drawn where the question asks for them or where they earn marks: the isomers of [Ma2b2] in Q5(a), octahedral splitting diagrams, van der Waals isotherms, the rate plot for reactants and products and the bcc unit cell.
8. Practical Links with the BCHCL 138 Lab
BCHCT 137 is taken together with the 2-credit lab course BCHCL 138, and several June 2026 theory questions sit right on top of that lab work.
Knowing the lab link helps in both directions. A student who has run a complexometric titration already understands why EDTA is polydentate, and one who has used a stalagmometer can name surface tension methods without thinking.
| BCHCL 138 lab work | Linked June 2026 question | What the link helps you write |
|---|---|---|
| Complexometric titrations with EDTA | Q4(a)(iv), EDTA as a ligand | Hands-on feel for how a titrant binds a metal ion, useful when you classify ligands |
| Composition of a complex by Job's method (Fe3+ with salicylic acid) | Q3(a) coordination number; Q7(iii) colour | How metal to ligand ratio and absorbance link to complex formation |
| Surface tension of a liquid or dilute solution using a stalagmometer | Q10 on liquids | Real readings behind the surface tension ideas the question tests |
The three above are the ones we have matched to this paper; check your BCHCL 138 manual for the full experiment list, including the viscosity and kinetics exercises that support Q10 and Q13.
9. Solved File Index
The full file answers all 14 questions of the June 2026 paper: 2 are on this page and 12 are in the paid file only.
| Question | Section | Marks split | Course unit | Where the answer is |
|---|---|---|---|---|
| Q1 | A | 2 × 2½ | Units 1 and 2 | Sample 1 above |
| Q2 | A | 5 | Unit 3 | Sample 2 above |
| Q3 | A | 3 + 2 | Unit 4 | Full file |
| Q4 | A | 3 + 2 | Unit 4 | Full file |
| Q5 | A | 3 + 2 | Units 5 and 7 | Full file |
| Q6 | A | 3 + 2 | Units 5, 6 and 7 | Full file |
| Q7 | A | 5 | Units 6 and 7 | Full file |
| Q8 | B | 2 + 3 | Unit 8 | Full file |
| Q9 | B | 2 + 3 | Unit 9 | Full file |
| Q10 | B | 3 + 2 | Unit 10 | Full file |
| Q11 | B | 2 + 3 | Unit 11 | Full file |
| Q12 | B | 2 + 3 | Units 11 and 12 | Full file |
| Q13 | B | 2 + 3 | Unit 13 | Full file |
| Q14 | B | 3 + 2 | Unit 14 | Full file |
Collecting more chemistry papers for the programme? Our BSCG Question Paper collection brings the other core courses together in one place.
10. Programmes That Include BCHCT 137
BCHCT 137 is a discipline-specific core chemistry course in IGNOU's BSCG programme and also appears in the BSCM scheme, as printed on the June 2026 paper.
In the Bachelor of Science (General) programme, BCHCT 137 is the fourth chemistry core after BCHCT 131, BCHCT 133 and BCHCT 135, each paired with its own lab course. It is normally studied once students have covered atomic structure, energetics and solutions in the earlier cores.
Students on Bachelor of Science (Multidisciplinary) write the same June 2026 paper under the combined BSCG and BSCM heading, so the questions, marks and answers in this file apply equally to both programmes; check your programme guide to confirm your semester.
11. How to Get the Full Solved Question Paper
Message WhatsApp 9899436384 with "BCHCT 137 June 2026" and our team will share the price and delivery details for the complete file.
The complete file answers all 14 questions: the 2 you have read here and the 12 listed above as full-file only, including both sides of every "or" choice in Q2, Q5, Q6 and Q7.
Inside you get the Q7 spin-state numerical, the Pc, Vc and Tc derivation, the bcc packing efficiency working and the collision theory comparison, all written to IGNOU mark weight.
12. BCHCT 137 FAQs
These answers cover the questions students ask most about the BCHCT 137 June 2026 solved paper.
Is the solved paper based on the official IGNOU question paper?
Yes. We used the official IGNOU June 2026 term-end paper for BCHCT 137, paper code D-4301, and kept every question exactly as printed. Our chemistry team then wrote complete answers for all 14 questions, including each "or" option, at the length a 2½ or 5 mark answer needs. The questions come from IGNOU; the answers, diagrams and worked numericals are ours.
How do I get all 14 answers on WhatsApp?
Send a message to WhatsApp 9899436384 with the code BCHCT 137 and the words June 2026. Our team replies with the price and delivery details. The full file answers all 14 questions of the paper: the 2 you can read on this page plus the 12 answered only in the file, along with every "or" option in Q2, Q5, Q6 and Q7.
Which questions are shown on this page and which are only in the file?
Q1 and Q2 from Section A are solved in full on this page. Q1 covers the colour of TiCl3 and TiO2, the softness of zinc and cadmium and the oxidation state of Cr in chromate, while Q2 compares lanthanoids with actinoids. Questions 3 to 7 of Section A and all seven Section B questions, 8 to 14, are answered only in the full file.
Which BCHCT 137 topics repeat most?
Across the official June 2022, December 2023 and June 2026 papers, 11 topics appeared every time. The strongest repeats are lanthanoid versus actinoid chemistry, isomerism of complexes, CFSE in weak and strong fields, the kinetic theory of gases, van der Waals critical constants, crystalline solids, packing efficiency and order of reaction. The repeat table on this page lists each topic by session.
How many marks and how much time does the exam carry?
The BCHCT 137 term-end paper carries 50 marks and runs for 2 hours. It has two sections of seven questions each. You attempt any five from Section A, which is coordination chemistry, and any five from Section B, which covers states of matter and chemical kinetics, on separate answer sheets. Every question carries 5 marks, so each section is worth 25.
Does the file show full working for numericals like Q7 and Q13?
Yes. Every numerical in the file is worked line by line with units. Q7 compares the pairing energy of Fe3+ with Δ0 for the aqua complex before deciding spin state, unpaired electrons and colour, and Q13 works out the order and the unit of k from the rate law. The derivations in Q8 and Q9 are also written step by step.
Is BCHCT 137 linked to a practical course?
Yes. In the BSCG programme guide, BCHCT 137 is a 4-credit theory course that must be taken together with BCHCL 138, a 2-credit laboratory course. Lab work such as complexometric titration with EDTA, Job's method for the composition of a complex and surface tension measurement connects directly to theory questions on ligands, complexes and liquids in the June 2026 paper.
Will the June 2026 answers help for the December 2026 exam?
They should help a lot. Many BCHCT 137 questions return from session to session with small changes. For example, the Zn and Cd softness question, the d7 CFSE question and the μ-dihydroxido cobalt formula appear in both December 2023 and June 2026. Practising these full answers prepares you for the same topics, though IGNOU can always set new questions.
13. Who Wrote and Checked the BCHCT 137 Answers
The BCHCT 137 answers were written by Prateek Talwar and reviewed by Sheetal Kirola.
Prateek Talwar, founder of Unnati Educations, leads the IGNOU science solved-paper series and prepares answers from the course blocks and the official term-end paper. Sheetal Kirola, Academic Head (M.Ed.), checks every term, symbol, configuration and unit against the BCHCT-137 blocks before release.