BSc Chemistry SEM III 2019 2020 Oct 2020 CHEMISTRY PAPER III Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q1 A. Fill in the blanks with suitable option and rewrite the statement (any TWELVE) 12 marks
   • 1) Semimicro- analysis refers to sample size of mg
   • 2) Accuracy stands for
   • (a) Precision
   • (b) Neutralization
   • (c) Reproducibility
   • 3) Acid base titrations are based on reactions. >
   • b) Neutralization is a Classical method
   • (a) Polarography
   • (b) Nephelometry
   • 5) is a separation technique
   • (a) Solvent extraction
   • (b) Polarography
   • (c) IR spectroscopy
   • 6) In gas liquid chromatography, mobile phase is
   • (a) Solid
   • (b) Liquid
   • (c) Gas
   • 7) Difference between end point and equivalence point is called as
   • (a) Absolute error
   • (b) Relative error
   • (c) Titration error
   • 8) Solution in flask is called
   • c) None of these
   • 9) Succinic acid is used as __ standard
   • (a) Primary
   • (b) Secondary
   • (c) tertiary
   • 10) In the titration of weak acid against strong base at equivalence point
   • 11) In titration of strong acid v/s weak acid,pH at equivalence point is CHEMISTRY P-III S.Y.B.Sc MARKS 100 TIME
   • 12) In titration of strong acid against weak base, pHat equivalence
   • (a) Greater tuan 7
   • (b) Less than 7
   • (c) Equal to 7
   • 13) Spectrophotometers use as a monochromator
   • (a) Filters
   • (b) Gratings
   • (c) Both filters and gratings
   • 14) Visible spectrometry use radiation in region of electromagnetic
   • 15) The photomultiplier tube is basically
   • (a) A photoemissive cell
   • (b) A photovoltaic cell
   • 16) Absorbance of the solution is (where are the intensity of incident and radiation respectively)
   • (b) Log I;/ Io
   • 17) According Beer-Lambert’s law the plot of absorbance versus concentration is a
   • (a) Straight line passing though origin with a positive slope passing through origin with a negative slope
   • (c) Straight line with positive slope and intercept on Y axis
   • 18) Introduction of an auxochrome a motecutestifts the absorption to
   • (a) Shorter wavelength
   • (b) Longer wavelength
   • (c) Higher wavelength state wether following statement is true or false
   • ii) All precipitates are heated to
   • iii) Beer-Lambert’s equation obeyed if the sample dissociates in solution
   • C. Match the following 5
   • 2. Methodic error (b) decrease in solubility CHEMISTRY MARKS 100 TIME 3HRS
   • 3. Common ion effect (c ) impurity in precipitate
   • 5. Conjugated compounds (e) shift to longer
2. Q2 answer the following: (any four) 20 marks
   • a. Explain sampling. What is the purpose of sampling?
   • b. Define: i) gross sampling ii) sampling unit iii) increment iv) sub sample v) analysis
   • c. calculate the mean and the median for the following sets of values
   • i) 6.10,6.12,6.14,6.10,6.12 and 6.14
   • ii) 18.30,18.28,18.32,18.27 and 18
   • d. What is sub-sample? Discuss coning and quartering method to reduce the sample size of solid sample
   • e. Describe any two types of sampling equipment employed in solid
   • f. Discuss the sampling of stationery and flowing liquids
3. Q3 Answer the following: (any four) 20 marks
   • a. Discuss the criteria for selection of an indicator in acid — base titrations
   • b. A sample of pure sodium carbonate, weighing 0.3542 g is dissolved in water and titrated with a solution of hydrochloric acid . Avolume of 30.23cm3 is fequired to reach the methy! orange end noint ,the being : —* Calculate the normality of the acid
   • c. Explain the conductometric titrations for i) strong acid vs strong base
   • d. Explain : how the following factors affect the solubility i)common ion effect
   • ii) pH Whai are acid base indicators? Expiain the use of different indicators for different
   • f. Explain the properties of colloidal precipitate which tend to stabilze it as a colloid
4. Q4 Answer the following: (any four) 20 marks
   • a. With the help of suitable diagram explain working of single beam colorimeter?
   • b. Write a note on photovoltaic cell
   • c. Describe the working of i) prism monochromator ii) diffraction grating monochromator CHEMISTPY MARKS 100 TIME
   • d. How are Cu(II) and estimated in a mixture using photometric titration?
   • e. Explain the calibration curve method of analysis. How is the concentration of unknown solution calculated without plotting the graph?
   • f. Discuss the principle and experimental set-up for performing photometric
5. Q5 Answer the following: (any four) 20 marks
   • a. Write on sampling of liquids
   • b. With the help of a suitable diagram explain tools used for sampling of gases
   • c. What are the various types of gravimetric titrations?
   • d. Write a note on co-precipitation and post precipitation?
   • e. State limitation and advantages of photometric titrations
   • f. Derive mathematical expression of Beer lamberts law

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