BSc Chemistry SEM IV 2018 19 May 2018-19 CHEMISTRY PAPER III Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q2 Figures to right indicate full marks
2. Q3 The use of log-table/nonprogrammable calculator is allowed A Select the correct option & complete the sentences (any TWELVE) (12)
3. Q1 Electrophoresis is a method il. is a chemical method of separation Solvent extraction is governed by law Iv. Chromatography consists of phases In chromatography value factor Vi. is a planar chromatographic technique Vil. Quinhydrone electrode is used as electrode in acid base When astrong base like is added to the solution of strong acid, pH of Ix. The unit of conductance is Xx. In conductometric titrations, is measured during the course of If the pH of the aqueous solution is 11.2, then it will be The plot of pH vs. volume of titrant xili, Variance is
   • xiv. Mode of the following set of normal error curve is plotted on Y - axis
   • a. observation b. frequency of occurrence c. mean
   • xvi. Confidence limit using range can be obtained by formula is used as rejection of the doubtful observation from the set
   • a. b. T - test c. Q - test xviii Null hypothesis is B State whether the following statements are true or false (any THREE) (03)
   • i. The partition coefficient and distribution ratio are always same il. Batch extraction method is used for solvent with small “D” value Potential of an indicator electrode remains constant Iv. Glass electrode is a type of ion selective electrode The process of finding, how dependent variables are linked to independent variable is known as regression analysis Vi. Variance ratio test is also known as Q - test Match the columns (Any FIVE) (05)
4. Q1 Distillation a. Rejection of result
5. Q2 Adsorbent b. Volatilization
   • h. Bell - shaped
6. Q2 Answer Any FOUR of the following 20 marks
   • a. What are the different types of separation methods? Explain any two of them
   • b. Prove that multiple extractions using small volume of extractant are more efficient than carrying out a single extraction involving same total volume
   • i. Explain the term “separation factor”
   • ii. When 0.1 dm? of an aqueous solution containing 0.2 g of a substance “S” is extracted with 0.5 dm? of ether; the ether layer was found to contain 0.186 g of “S”. Calculate distribution ratio (Dow) in favour of ether,
   • d. Describe the preparation of plates used in TLC. What are the other steps
   • e. 100 cm? of aqueous solution containing 100 pg of substance “M”. the solution is to be extracted with an organic solvent. If the distribution ratio D
   • (i) The extraction efficiency for five extractions using 100 cm? solvent
   • (ii) the minimum number of extractions using solvent to leave lug of
   • f. What are the different methods used for the development of chromatogram in paper chromatography? Explain any one of it in detail with suitable diagram
7. Q3 Answer Any FOUR of the following 20 marks
   • a. Describe different methods used to determine the equivalence point from the “S” shape graph of vs. volume of titrant added
   • b. What are the advantages and limitations of conductometric titrations?
   • c. Describe construction and working of glass electrode
   • d. What is the principle of conductometric titration? Give an account of conductivity cell with a neat and labelled diagram
   • e. Explain the terms with suitable examples and give electrode representation:
   • f. What is the principle of pH—metry? Give an account of titration curve when a strong acid is neutralized by a strong base using pH meter
8. Q4 Answer Any FOUR of the following 20 marks
   • a. What is variance ratio test? Following are the two sets of observations for analysis of calcium in the given sample of limestone by two independent methods. Verify whether the two standard deviations are same or different
   • b. What are the salient features of Gaussian distribution curve? The following table gives dependence of y on x Assuming a linear relationship between the variables make least square analysis of the data to derive an equation of the type y = mx
   • d. What is What are the different steps involved in Q — Test? In the analysis of a sample for its Fe content, the values reported are: 4.5, 4.7, 4.6 and 4.9. on the basis of 2.5 d rule and 4.0 d rule, find whether the value 4.9 can be retained or rejected
   • f. The following results were obtained in the replicate analysis of the samples of blood for its lead content If the combined standard deviation value is 0.004. Find whether the two methods differ statistically or only numerically
9. Q5 Answer Any FOUR of the following 20 marks
   • a. Explain the term chromatography. Give classification of chromatogra- phic methods on the basis of nature of phases involved in it
   • b. What are the criteria for selection of an extracting solvent? Explain any two applications of conductometry in neutralization titrations
   • d. What are the different types of pH meters? What is the use of pH metry in
   • e. Five replicate measurements for the determination of iron in the sample gave the following results: 15.63, 15.68 and 15.64 Calculate 95% confidence limit for the mean if
   • i. No additional information about the precision of the method is known
   • ii. A large number of measurements have given o = 0.02 (t = 2.78, Z = 1.96 at 95% confidence limit.)
   • f. In six lead determinations from the sample, each of which contain 400 mg of Lead, the following results were obtained Calculate the mean , median, range, average deviation and standard

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