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)
   • 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
   • a) Precipitation
   • b) Neutralization
   • 4) is a classical method
   • (a) Polarography
   • (c) Gravimetry
   • 5) is a separation technique
   • (a) Solvert 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 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 CHEMISTRY P-III SEM-III MARKS 100 TIME 3HRS
   • 11) In titration of strong acid v/s weak acid,pH at equivalence point is
   • 12) In titration of Strong acid against weak base, pHat equivalence point is
   • (a) Greater than 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
   • 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 I a motecuteshifts the absorption to
   • (a) Shorter wavelength
   • (b) Longer wavelength
   • (c) Higher wavelength
   • B. State whether following statement is true or false, 3
   • i) Classical methods are more accurate and sensitive in comparison to instrumental
   • ii) Phenolphthalein can be used for all acid —base titrations.
   • iii) s to s* transition is possible with UV radiations CHEMISTRY P-III MARKS 100 TIME 3HRS
   • C. Match the following 5
   • 1. Relative error (a) shift to longer wavelengh
   • 3. Diverse ion effect (c) solubility of precipitation
2. Q2 Answer the (any four) 20 marks
   • a. Discuss sampling of liquids in brief
   • b. Define: i) gross sampling ii) sampling unit iii) increment iv) sub sample v) analysis
   • c. What is sub-sample? Discuss coning and quartering method to reduce the sample size of solid sample
   • d. Explain any two types of sampling equipment employed in solid With the help of a suitable diagram explain tools used for sampling of gases
   • f. Explain sampling. What is the purpose of sampling?
3. Q3 Answer the following: (any four) 20 marks
   • a. What is co-precipitation and post precipitation?
   • b. Explain : how the following factors affect the solubility ion effect
   • ii) pH Distinguish between primary standard and secondary standard
   • d. Explain the theory of acid base theory. What are acid base indicators? Explain the use of different indicators for different acid
   • f. Explain the conductometric titrations for i) strong acid vs strong base CHEMISTRY P-III MARKS 100 TIME 3HRS
4. Q4 Answer the following: (any four) 20 marks
   • a. Derive mathematical expression of Beer lamberts law
   • b. With the help of suitable diagram explain working of single beam colorimeter?
   • c. Discuss the principle of photometric titrations
   • d. With the help of suitable diagram explain working of double beam spectrophotometer?
   • e. Explain the calibration curve method of quantitative analysis. How is the concentration of unknown solution calculated without plotting the graph?
   • f. Describe the working of i) prism monochromator ii) diffraction grating monochromator
5. Q5 Answer the following: (any four) 20 marks
   • a. 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
   • b. Discuss the methods of minimizing errors
   • c. What are the properties of colloidal precipitate which tend to stabilze it as a colloid
   • d. Write a note on drying and ignition of the precipitate
   • e. Explain the working of “photovoltaic cell”
   • f. State limitation and advantages of photometric titrations

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