IGNOU MCH 25 SOLVED ASSIGNMENT

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MCH 025 (January 2026 - July 2026) - ENGLISH

Tutor Marked Assignment
Electroanalytical and other Analytical Methods (MCH-025)

Course Code: MCH-025
Assignment Code: MCH-025/TMA/2026
Maximum Marks: 100

Note: Attempt all questions. The marks for each question are indicated against it.

1. (a) Give a difference between: 
(i) oxidation and oxidizing agent
(ii) reduction and reducing agent
(iii) a galvanic cell and an electrolytic cell
(iv) voltammetry and polarography

(b) Consider the following electrochemical cell 
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(i) Write the cell reaction.
(ii) Calculate the EMF of the cell. Where,
and

2. (a) What is Coulometer? Explain briefly. Write cathodic and anodic reaction of hydrogen-nitrogen coulometer, where 0.1 M hydrazine sulphate is used as the electrolyte. 

(b) In a coulometric method, 200 mg of nitrobenzene in of methanol is reduced to phenyl hydroxylamine at a constant potential of -0.95 V (vs. SCE) applied to an Hg electrode. Following reaction takes 30 minutes to complete.
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Calculate the percentage of nitrobenzene if above reduction requires 32mA current. 

3. (a) What is dropping mercury electrode? Give its advantages. 

(b) Indium and Cadmium ions in 0.1 M HCl give peaks at potentials -0.557 V and -0.597 V by differential pulse polarographic analysis. When a standard solution containing 0.4 ppm of indium is analysed, it gave peak current (in arbitrary units) corresponding to 100.25 at -0.557 V and 43.75 at -0.597 V. A standard solution containing 0.4 ppm of Cd gave i_p 29.52 at -0.557 V and 64.8 at -0.597 V. What is the concentration of indium and cadmium in a sample if the peak current is 190 at -0.557 V and 120 at -0.597 V. 

4. (a) What are amperometric titrations? Draw common types of curves obtained in amperometric titrations. What will be the shape of the curve in bioamperometry for the titration of iodine by thiosulphate? 

(b) What is common source of errors in thermogravimetric analysis (TGA)? A mixture of CaO and is analysed by TGA. The result indicates that mass of the sample decreases from to only between and . Calculate the percentage of calcium carbonate in the mixture. 

5. (a) Explain how thermometric titrations are different than classical titrations. Discuss their advantages. 

(b) What is the principle of differential scanning calorimetry (DSC)? Draw the schematic diagram of a DSC instrument. 

6. (a) How many and particles will be emitted in following successive decays.
(i)
(ii)
(iii)
(iv)  

(b) What are the common sources of neutron for neutron activation analysis (NAA)? What factors contribute to higher sensitivity in NAA? Briefly explain any one. 

7. (a) Explain why neutron induced reactions are most common whereas deuteron induced reactions require accelerator facility to carry out these reactions. 

(b) In an isotope dilution analysis experiment, radiolabelled analyte with specific activity was added. After equilibration and chemical separation pure analyte having specific activity was isolated. Calculate the amount of analyte in the sample. 

8. (a) What is the difference between SEM and TEM? Write the advantages of TEM over SEM? 

(b) Which components are used in the X-ray photoelectron spectroscopy (XPS) instrument? Briefly explain with a schematic diagram of XPS Instrumentation. 

9. (a) What information does the energy dispersive spectroscopy (EDS) provide? Write any three applications of EDS. 

(b) Briefly explain the basic principle of Auger Electron Spectroscopy (AES) with a suitable diagram. 

10. (a) Write the basic principle of Rutherford backscattering spectroscopy (RBS) also name the ions commonly used for primary beam in RBS. 

(b) How does atomic force microscopy (AFM) work? Explain briefly with their applications. 

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