IGNOU BCHET-141 (January 2025 – December 2025) Assignment Questions
Par A
1 Writ the procedure for the sampling of soil samples.
2 Define determinate errors. How we can reduce them.
3 What is significance of F-test? Explain using a suitable example.
4 Briefly explain the extractions with diphenylthiocarbazone. How is change in pH useful in such extractions?
5 Discuss the extraction of an organic compound when it is present in the aqueous phase along with the impurities.
6 How is extraction of metal chlorides and nitrates carried out using solvation?
7 How can a mixture of three components be separated using ascending paper chromatography? Draw the suitable diagram and explain.
8 Give at least five examples each of mobile phases and locating agents used in paper chromatography
9 Briefly explain various factors affecting the efficiency of column chromatography
10 Why is selectivity coefficient of an ion exchanger important? Give the order of selectivity coefficients of different cations and anions.
Par B
11 Drive an expression for the ‘operational definition of pH.
12 Discuss design and working of calomel and glass electrodes.
13 Describe different factors effecting conductance.
14 A conductivity cell shows a resistance of 3950 Ω at 25oC when filled with the experimental solution and 4864 Ω at the same temperature when filled with 0.02 M KCl solution. If the conductivity of the solution is 2.767 x 10-3 S cm-1, calculate the conductivity of the experimental solution.
15 Describe the experimental setup of TGA. Taking suitable examples explain the effect of furnace atmosphere on TG curves.
16 An impure sample of CaC2O4 H2O is analyzed using TGA technique. TG curve of the sample indicates the total mass change from 85 mg to 30.7 mg when this sample was heated up to 1173 K. calculate the purity of the sample.
17 (a) Define electromagnetic radiation and state the relationship between the velocity and wavelength of an electromagnetic radiation.
(b) Molecular spectra are band spectra whereas atomic spectra are line spectra. Explain.
18 (a) State Beer and Lambert’s law and write its mathematical expression.
(b) What are monochromators? Explain the working of prism monochromator with the help of a suitable diagram.
19 (a) Calculate the number of vibrational degrees of freedom for ethane, C2H6, explain the fingerprint and functional group regions in IR spectrum.
(b) Outline the advantages of premix burner in atomic spectroscopy. Discus structure of a laminar flow flame showing various zones.
20 List different excitation sources used for atomic emission spectrometry. Discuss the interferences observed in flame atomic emission Spectrometry
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IGNOU BCHET-141 (January 2024 – December 2024) Assignment Questions
Part A
1. Writ the procedure for the collection and preservation of water samples.
2. Define Indeterminate errors. How we can reduce them.
3. What is significance of t-test? Explain using a suitable example.
4. Which reagents are used for extraction by solvation? Give suitable examples.
5. Briefly explain the extraction by chelation. Also give some examples of the chelating agents used.
6. Explain continuous extraction with the help of a suitable diagram. Which factors govern the efficiency of such extractions?
7. Draw a flow chart for the classification of various types of chromatographic techniques.
8. List different criteria for choosing the mobile phase used in paper chromatography.
9. Discuss the principle of coloumn chromatography illustrating the experimental setup.
10. Briefly explain various types of capacities associated with ion exchangers.
Part B
11. Discuss the factors which limit the accuracy of pH measurements.
12. Discuss design and working of silver-silver chloride electrode.
13. How the conductance is varies with concentration? Explain with the help of suitable examples.
14. Explain ionic nobilities and transport number.
15. Taking suitable examples explain the effect of furnace atmosphere on TG curves.
16. An impure sample of CaC2O4, H2O is analyzed using TGA technique. TG curve of the sample indicates the total mass change from 85 mg to 30.7 mg when this sample was heated up to 1173 K. calculate the purity of the sample.
17. Write the shortcomings of wave model of electromagnetic radiation. Describe the model that was able to explain these shortcomings.
18. Write the expression of Lambert’s and Beer’s law. List the factors responsible for the deviation from Beer-Lambert’s law.
19. What is the necessary condition for observing IR spectrum? Describe in brief the types of vibrations for a polyatomic molecule.
20. How are the signals in an atomic spectrum characterized? Illustrate your answer.
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