MCH 013 Solved Guess Paper gives you 14 high-probability questions with complete, exam-ready answers for General Physical Chemistry, written for the December 2026 term-end exam. It is built for learners of IGNOU's Master of Science (Chemistry) (MSCCHEM) and Master of Science in Analytical Chemistry (MSCANCHEM), where MCH-013 is a core first-semester course.
Before writing a single answer, our team went through five years of MCH-013 papers, including the December 2025 and June 2026 sessions, and marked every topic that came back. The answers are plain, point-wise and matched to the IGNOU blocks, so you can revise a 10-mark question in about fifteen minutes.
MCH 013 Guess Paper Key Facts
- Course: MCH-013 General Physical Chemistry
- Programmes: MSCCHEM and MSCANCHEM (IGNOU)
- Syllabus: 4 blocks, 16 units
- Exam: 2 hours, 50 marks
- Paper format: Q1 compulsory (any five 2-mark parts) + any four of Q2 to Q7
- Guess paper: 14 solved questions across 22 pages
- On this page: 5 sample answers; the other 9 come in the full file
- Target exam: December 2026 term-end exam
- Order on WhatsApp: 9899436384
What the MCH 013 Guess Paper Is and Who It Helps
The MCH 013 Guess Paper is a 22-page answer booklet of 14 likely exam questions for IGNOU's General Physical Chemistry course, mapped to all four blocks of the syllabus.
MCH-013 General Physical Chemistry covers thermodynamics, statistical thermodynamics, solid state, reaction rate theories, catalysis, enzyme kinetics, Debye-HΓΌckel theory and transport phenomena. That is a lot of derivations for a 2-hour paper, and most learners lose marks not on concepts but on writing them out in the right order.
This booklet fixes that. Each question comes with a priority tag, its block and unit, the sessions it last appeared in, and a word target so you know how much to write. It belongs to our wider range of IGNOU Solved Guess Paper titles, but every question here was chosen from MCH-013 patterns only.
It helps three kinds of learners most: working professionals with two weeks to revise, students repeating the course after a low score, and anyone who finds physical chemistry derivations hard to structure under time pressure.
MCH 013 Solved Guess Paper Sample Questions with Answers
Five of the 14 questions are shown below with their full answers, so you can check the depth, language and layout before ordering the complete file.
We picked samples from four different blocks. Every one of these topics was asked in the December 2025 paper, so they are also a quick revision set on their own.
Chemical Potential and Partial Molar Volume of an Ideal Gas
Question: Write the expression for chemical potential and explain its physical significance. Show that for an ideal gas in a mixture the partial molar volume equals RT/P.
(a) Expression. The chemical potential of component i is the change in Gibbs energy when one mole of i is added at constant temperature, pressure and amounts of all other components: ΞΌi = (βG/βni)T, P, nj. For a pure substance, ΞΌ equals the molar Gibbs energy, Gm.
Physical significance:
- It measures the escaping tendency of a substance from one phase to another.
- It is the driving force for mass transfer and chemical reaction.
- Matter moves spontaneously from higher to lower chemical potential.
- At equilibrium, a component has the same chemical potential in every phase.
- It decides the direction of diffusion, phase equilibrium and chemical equilibrium.
(b) Derivation. For an ideal gas mixture, V = nRT/P, where n = n1 + n2 + n3 + β¦ The partial molar volume is VΜi = (βV/βni)T, P, nj. Differentiating (n1 + n2 + β¦)RT/P with respect to ni, while R, T, P and all other nj stay constant, gives VΜi = RT/P.
So every component of an ideal gas mixture has the same partial molar volume, RT/P, whatever the nature of the gas.
Lindemann-Christiansen Theory of Unimolecular Reactions
Question: Write the steps of the Lindemann-Christiansen theory with the rate equation of each step. Identify the rate-determining step at high pressure and outline the limitations of the theory.
The theory says a unimolecular reaction goes through an energised molecule A*, formed by collision, which either loses its energy or breaks down into products.
- Activation: A + A β A* + A (rate constant k1); rate = k1[A]2
- Deactivation: A* + A β A + A (rate constant kβ1); rate = kβ1[A*][A]
- Product formation: A* β Products (rate constant k2); rate = k2[A*]
Applying the steady-state approximation to A* gives [A*] = k1[A]2 / (kβ1[A] + k2), so the overall rate = k1k2[A]2 / (kβ1[A] + k2).
High pressure: collisions are frequent, so kβ1[A] β« k2 and rate = (k1k2/kβ1)[A]. The reaction is first order and step 3, the breakdown of A*, is rate-determining. At low pressure the rate becomes k1[A]2, so activation controls the rate and the order becomes two.
Limitations:
- The predicted fall-off of the rate constant with pressure does not match experiment at low pressures.
- k1 calculated from simple collision theory is far smaller than the observed value.
- It ignores how energy is spread over the internal vibrational modes of the molecule.
- It treats every energised molecule as equally likely to react, whatever its excess energy.
- Hinshelwood, RRK and RRKM theories were developed to remove these gaps.
Michaelis-Menten Mechanism, Michaelis Constant and Turnover Number
Question: Describe the Michaelis-Menten mechanism for an enzyme-substrate system. Explain why the rate changes from first order to zero order, and state the significance of the Michaelis constant and the turnover number.
The enzyme E binds the substrate S to form a complex ES, which breaks down to product P and releases the enzyme: E + S β ES (k1, kβ1), then ES β E + P (k2). With the steady-state approximation on ES, the rate is v = Vmax[S] / (Km + [S]), where Km = (kβ1 + k2)/k1.
First order to zero order. When [S] βͺ Km, most active sites are empty, so v β (Vmax/Km)[S] and the rate is first order in substrate. When [S] β« Km, nearly every active site is occupied and v β Vmax. Adding more substrate cannot raise the rate, so the reaction becomes zero order. The physical reason is enzyme saturation.
Significance of Km:
- It is the substrate concentration at which v = Vmax/2.
- It indicates enzyme-substrate affinity: a small Km means high affinity.
- It lets you compare how different enzymes, or one enzyme with different substrates, perform.
Turnover number. kcat = Vmax/[E]0 is the number of substrate molecules one enzyme molecule converts per second at saturation. A higher kcat means a more efficient catalyst, and kcat/Km is used as a combined measure of enzyme efficiency.
Primary Salt Effect and the BrΓΈnsted-Bjerrum Equation
Question: Explain the primary salt effect on ionic reactions in solution. Give the BrΓΈnsted-Bjerrum equation and discuss the effect of ionic strength on the rate constant for the possible cases.
The primary salt effect is the change in the rate constant of a reaction between ions when the ionic strength of the solution changes. Added ions alter the activity coefficients of the reacting ions, as the Debye-HΓΌckel theory predicts, and so alter the rate.
BrΓΈnsted-Bjerrum equation: log k = log k0 + 2A zAzBβI, where 2A β 1.02 for water at 25 Β°C, k0 is the rate constant at zero ionic strength, zA and zB are the ionic charges, and I = Β½ Ξ£ cizi2. A plot of log(k/k0) against βI is a straight line with slope 1.02 zAzB.
| Case | Sign of zAzB | Rate constant as I rises | Example and slope |
|---|---|---|---|
| Like-charged ions | Positive | Increases | [Fe(CN)6]4β + S2O82β: zAzB = +8, steep positive slope |
| Oppositely charged ions | Negative | Decreases | [Co(NH3)5Cl]2+ + OHβ: zAzB = β2, negative slope |
| Ion with a neutral molecule | Zero | Stays unchanged | CH3I + OHβ: zero slope |
| Two neutral molecules | Zero | Independent of I | CH3I + H2O: zero slope |
In short, like charges speed up and opposite charges slow down as ionic strength rises, while reactions involving a neutral species show no primary salt effect.
Debye-HΓΌckel Theory, Debye Length and Limitations
Question: State the basic assumptions of the Debye-HΓΌckel theory. What is the Debye length? Outline the limitations of the theory.
Assumptions:
- The strong electrolyte is fully dissociated into ions.
- Ions are point charges; their size is neglected.
- The solvent is a continuum with a constant dielectric constant.
- Each ion is surrounded by a spherically symmetric ionic atmosphere of net opposite charge.
- Ions are distributed according to the Boltzmann distribution.
- Only long-range electrostatic forces act; short-range forces are ignored.
- The electrostatic energy is small compared with kT, which holds in dilute solutions.
Debye length. The Debye length, 1/ΞΊ, is the effective radius of the ionic atmosphere around a central ion. It varies as β(Ξ΅T/I), so it shrinks as ionic strength rises. For a 1:1 electrolyte in water at 25 Β°C, 1/ΞΊ β 0.304/βI nm, which is about 3 nm at 0.01 M. A shorter Debye length means stronger screening of the central ion.
Limitations:
- The limiting law holds only in very dilute solutions, roughly below 0.01 M for 1:1 electrolytes.
- Treating ions as point charges fails once ionic size becomes comparable to 1/ΞΊ.
- Ion-solvent interactions and changes in dielectric constant near ions are ignored.
- It cannot explain why activity coefficients rise again at high concentration.
- It does not account for ion pairing or specific ion effects, especially with highly charged ions.
Full Question Index of the IGNOU MCH 013 Guess Paper
The IGNOU MCH 013 Guess Paper holds 14 solved questions: 10 long answers worth 10 marks and 4 short answers worth 5 marks, spread across all four blocks.
| Q | What the answer covers | Block and unit | Marks | On this page |
|---|---|---|---|---|
| 1 | Significance of Maxwell relations and derivation of all four from dU, dH, dA and dG | Block 1, Unit 1 | 10 | Full file |
| 2 | Chemical potential expression and proof that partial molar volume equals RT/P | Block 1, Unit 2 | 10 | Sample 1 |
| 3 | Stirling's approximation for ln n!, where it helps and where it fails for small n | Block 1, Unit 3 | 5 | Full file |
| 4 | Permutation vs configuration, W = N!/Ξ ni! and probability of a configuration | Block 1, Unit 3 | 10 | Full file |
| 5 | Characteristics of unimolecular reactions and pressure-dependent order | Block 2, Unit 8 | 5 | Full file |
| 6 | Lindemann-Christiansen steps, steady-state rate law and limitations | Block 2, Unit 8 | 10 | Sample 2 |
| 7 | Hinshelwood's modification and how internal degrees of freedom improve the model | Block 2, Unit 8 | 5 | Full file |
| 8 | Catalyst definition, homogeneous vs heterogeneous catalysis, equilibrium constant | Block 3, Unit 11 | 10 | Full file |
| 9 | Michaelis-Menten mechanism, enzyme saturation, Km and kcat | Block 3, Unit 12 | 10 | Sample 3 |
| 10 | Continuous flow and stopped flow principles, working and comparison | Block 3, Unit 10 | 10 | Full file |
| 11 | Relaxation methods, relaxation time Ο = 1/(kf + kr), T-jump and P-jump | Block 3, Unit 10 | 5 | Full file |
| 12 | Primary salt effect, BrΓΈnsted-Bjerrum equation and slope for each charge case | Block 3, Unit 9 | 10 | Sample 4 |
| 13 | Debye-HΓΌckel assumptions, Debye length and limitations | Block 4, Units 13 and 14 | 10 | Sample 5 |
| 14 | Flux, mean free path vs pressure, four transport laws, Fick's first and second laws | Block 4, Units 15 and 16 | 10 | Full file |
Five questions are open above, and the remaining 9 unlock when you order the full file.
MCH 013 General Physical Chemistry Syllabus by Block and Unit
MCH 013 General Physical Chemistry has 4 blocks and 16 units, running from Gibbs and Helmholtz functions in Unit 1 to thermal and ionic conduction in Unit 16.
The block and unit titles below follow the course listing on IGNOU eGyanKosh. The third column lists the topics that examiners have actually pulled from each unit, so you can see where the marks sit.
| Block | Unit | Key topics to revise |
|---|---|---|
| Block 1: Thermodynamics and Statistical Thermodynamics | Unit 1: Gibbs and Helmholtz Functions | Maxwell relations, ΞG for isothermal expansion, spontaneity from ΞH and ΞS |
| Block 1: Thermodynamics and Statistical Thermodynamics | Unit 2: Systems of Variable Composition | Chemical potential, partial molar volume, escaping tendency |
| Block 1: Thermodynamics and Statistical Thermodynamics | Unit 3: Introduction to Statistical Thermodynamics-I | Configurations and weights, Stirling's approximation, molecular partition function |
| Block 2: Solid State and Reaction Rate Theories | Units 4 to 7: Solid state | Miller indices, interplanar spacing in orthorhombic cells, tetrahedral and octahedral voids, diffraction |
| Block 2: Solid State and Reaction Rate Theories | Unit 8: Theories of Unimolecular Reactions | Lindemann-Christiansen steps, Hinshelwood modification, fall-off behaviour |
| Block 3: Kinetics and Catalysis | Unit 9: Kinetics of Reactions in Solution | Primary salt effect, ionic strength, BrΓΈnsted-Bjerrum plots |
| Block 3: Kinetics and Catalysis | Unit 10: Kinetics of Fast Reactions | Stopped flow vs continuous flow, T-jump, rate constants from relaxation time |
| Block 3: Kinetics and Catalysis | Unit 11: Catalysis | Potential energy profiles, surface-catalysed unimolecular rate law, catalyst and K |
| Block 3: Kinetics and Catalysis | Unit 12: Kinetics of Enzyme Reactions | Michaelis-Menten equation, Km, turnover number |
| Block 4: Electrochemistry and Transport Phenomenon | Unit 13: Debye-HΓΌckel Theory-I | Ionic atmosphere, Debye length, model assumptions |
| Block 4: Electrochemistry and Transport Phenomenon | Unit 14: Debye-HΓΌckel Theory-II | Limiting law, mean ionic activity coefficient of NaCl, validity range |
| Block 4: Electrochemistry and Transport Phenomenon | Unit 15: Transport Phenomenon-I: Diffusion and Viscosity | Flux, mean free path, Fick's first and second laws |
| Block 4: Electrochemistry and Transport Phenomenon | Unit 16: Transport Phenomenon-II: Thermal and Electrical (Ionic) Conduction | Pressure-independent thermal conductivity, how electrical transport differs |
The guess paper answers theory from Blocks 1, 3 and 4 and Unit 8 of Block 2. For crystal geometry numericals from Units 4 to 7, keep your MCH 013 Study Material open alongside it, because those questions are best practised with the unit examples.
MCH 013 Exam Pattern for December 2026
MCH-013 is a 2-hour, 50-mark paper: Question 1 is compulsory, where you answer any five 2-mark parts, and you then attempt any four of Questions 2 to 7, each worth 10 marks.
| Part | What you attempt | Marks | How the guess paper helps |
|---|---|---|---|
| Question 1 | Any five short parts (seven were offered in December 2025) | 5 Γ 2 = 10 | The 5-mark answers on Stirling, unimolecular traits and relaxation give ready 2-mark lines |
| Questions 2 to 7 | Any four, each split into 2 to 4 mark sub-parts | 4 Γ 10 = 40 | The 10-mark answers split cleanly into sub-parts like steps, derivation and limitations |
| Total | Theory, derivations and numericals | 50 | Constants such as kB, h, NA and R are printed on the paper |
This structure is confirmed from the official December 2025 MCH-013 question paper. Because sub-parts are small, a clean, labelled answer scores better than a long essay.
MCH 013 Important Questions That Keep Repeating
Chemical potential, catalysis, Michaelis-Menten kinetics and flow methods appeared in all three sessions from December 2024 to December 2025, making them the safest MCH 013 important questions for December 2026.
| Topic | Dec 2024 | Jun 2025 | Dec 2025 | Guess paper Q |
|---|---|---|---|---|
| Chemical potential and partial molar volume | Yes | Yes | Yes | Q2 |
| Catalysis and potential energy profiles | Yes | Yes | Yes | Q8 |
| Michaelis-Menten enzyme kinetics | Yes | Yes | Yes | Q9 |
| Stopped flow and continuous flow | Yes | Yes | Yes | Q10 |
| Stirling's approximation | No | Yes | Yes | Q3 |
| Microstates and configuration probability | Yes | No | Yes | Q4 |
| Lindemann-Christiansen theory | No | Yes | Yes | Q6 |
| Relaxation methods and relaxation time | No | Yes | Yes | Q11 |
| BrΓΈnsted-Bjerrum plots | Yes | No | Yes | Q12 |
| Debye-HΓΌckel limitations and Debye length | No | Yes | Yes | Q13 |
| Flux, mean free path and Fick's laws | Yes | Yes | Yes | Q14 |
| Characteristics of unimolecular reactions | No | No | Yes | Q5 |
| Hinshelwood's theory | Yes | No | No | Q7 |
| Maxwell relations | Yes | No | No | Q1 |
Frequency is only half the picture. Topics like Hinshelwood's theory and Maxwell relations have skipped two sessions, and gaps like that often return. Checking the actual wording in our IGNOU Previous Year Question Paper collection shows how the same idea gets asked from a new angle.
One honest note: December 2025 also carried numericals, such as the percentage error of Stirling's approximation for 6!, forward and reverse rate constants from a 5 s relaxation time, and the mean ionic activity coefficient of 0.01 M NaCl. Use the theory answers here to understand the formula, then practise those calculations from past papers.
15-Day Revision Plan with the MCH 013 Guess Paper
Spend the first 12 days on two or three guess paper questions a day by block, and keep the last 3 days for numericals and one timed mock paper.
- Days 1 to 3, Block 1: Q1 to Q4. Write the four Maxwell relations from memory and redo the W = N!/Ξ ni! working once.
- Days 4 to 5, Block 2: Q5 to Q7. Draw the pressure versus order summary for Lindemann in one line.
- Days 6 to 9, Block 3: Q8 to Q12. Make a slope chart for five BrΓΈnsted-Bjerrum pairs and sketch a catalysed energy profile.
- Days 10 to 12, Block 4: Q13 and Q14. Learn the Debye length expression and write both Fick's laws with units.
- Days 13 to 14: Solve the December 2025 numericals: Stirling error, relaxation rate constants and mean activity coefficient.
- Day 15: Attempt one full paper in 2 hours and mark any answer that ran over its word target.
General Physical Chemistry Important Questions stick better when you write them, not just read them. Even 250 handwritten words per question during this plan will make exam day feel familiar.
Why Students Choose Our MCH 013 Solved Guess Paper
Every answer is checked against the IGNOU MCH-013 blocks and the recent question papers, so what you revise matches both the book and the way questions are really asked.
Unnati Educations, based in Vikaspuri, Delhi, has prepared IGNOU study support for years, and this file follows the same process as our other science titles: past paper analysis first, then answer drafting, then a syllabus review. If you are preparing more first-semester courses, our MSCCHEM Guess Paper range uses the same layout.
- Exam-first selection: questions are picked from repeat patterns, not copied from the table of contents.
- Sub-part friendly answers: steps, derivation and limitations are separated, the way 2 to 4 mark sub-parts are set.
- Plain language: short sentences that are easy to reproduce in your own words.
- Direct support: doubts about any answer can be sent on WhatsApp to 9899436384.
The page was written by Prateek Talwar and reviewed by Sheetal Kirola for syllabus alignment and exam-pattern accuracy.
How to Get the Full IGNOU MCH 013 Guess Paper
Send "MCH-013" on WhatsApp to 9899436384 and our team will share the complete 22-page file with all 14 solved questions.
- Tap the button below or save 9899436384 and open WhatsApp.
- Type the course code MCH-013 and mention whether you are in MSCCHEM or MSCANCHEM.
- Confirm the December 2026 edition and complete the order details our team shares.
- Receive the PDF and start with the four topics that repeated in all three sessions.
MCH 013 Guess Paper FAQs
What is the MCH 013 Solved Guess Paper?
It is a 22-page booklet from Unnati Educations with 14 likely questions and complete answers for IGNOU's MCH-013 General Physical Chemistry course. Questions were selected by analysing recent term-end papers, and each answer is mapped to its block and unit. It is designed for learners taking the December 2026 exam who want structured, point-wise answers they can revise quickly.
Is the IGNOU MCH 013 Guess Paper useful for the December 2026 exam?
Yes. The file targets the December 2026 term-end exam and follows the current 2-hour, 50-mark pattern, with Question 1 compulsory and any four from Questions 2 to 7. Four of its topics appeared in all three sessions from December 2024 to December 2025, so the paper focuses your time on areas examiners return to most often.
How many questions are in the MCH 013 Guess Paper?
The guess paper has 14 solved questions: 10 long answers worth 10 marks and 4 short answers worth 5 marks. They cover all four blocks of the syllabus. Five of these answers are shown on this page as samples, and the remaining 9 are included when you order the complete PDF through WhatsApp on 9899436384.
Which MCH 013 Important Questions repeat most often?
Chemical potential with partial molar volume, catalysis, Michaelis-Menten enzyme kinetics and stopped flow versus continuous flow methods appeared in December 2024, June 2025 and December 2025. Lindemann-Christiansen theory, Stirling's approximation, relaxation methods and Debye-HΓΌckel theory each appeared twice in the same period. All of these topics are answered in full inside the guess paper file, with block and unit references for quick revision.
Does the MCH 013 Guess Paper include numericals?
The guess paper is mainly theory and derivations, which carry most of the marks. It explains the formulas behind common numericals, such as Stirling's approximation and relaxation time. For calculation practice, solve the numericals from recent MCH-013 papers too, including the December 2025 questions on percentage error, rate constants and mean ionic activity coefficient, under a timed setting.
Can MSCANCHEM students use the MCH 013 Guess Paper?
Yes. MCH-013 General Physical Chemistry is common to both IGNOU's M.Sc. Chemistry (MSCCHEM) and M.Sc. Analytical Chemistry (MSCANCHEM) programmes, and both sit the same term-end paper. The questions, answers and exam pattern in this guess paper apply equally to learners from either programme, so no separate edition is needed. Just mention your programme when you place the order on WhatsApp.
How do I get the full MCH 013 Guess Paper PDF?
Send the course code MCH-013 on WhatsApp to 9899436384 and mention your programme, MSCCHEM or MSCANCHEM. Our team will confirm the December 2026 edition and share the order details. Once the order is complete, you receive the full 22-page PDF with all 14 solved questions, and you can message the same number with any doubts.
Is the MCH 013 Solved Guess Paper an official IGNOU publication?
No. It is an independent study aid prepared by Unnati Educations and is not published or endorsed by IGNOU. Answers follow the official MCH-013 blocks and recent term-end papers, but questions in your exam may differ. Use it alongside the IGNOU study material and recent past papers rather than as a replacement for them, especially for numericals.