General Practical Chemistry I — 2021 Past Questions

University of Ilorin CHM107: 47 questions.

Topics: Precipitation Titration, Volumetric Analysis, Oxidation-Reduction Titration, Scientific Data and Chemical Experiments, Treatment of Analytical Data, Acid-Base Titration

1. Dimercapto-1-propanol is a
   1. masking agent
   2. demasking agent
   3. chelating agent
   4. reducing agent
2. The mole ratio of acid to base in the reaction between CH₃COOH and Ba(OH)₂ is
   1. 1:1
   2. 4:2
   3. 2:1
   4. 1:2
3. Ammonium ion forms insoluble salt with which of the following
   1. carbonate
   2. sulphate
   3. chloride
   4. none of these
4. What is the correct order of steps in analytical chemistry?
   1. Formulating question, selecting analytical procedure, sampling, sample preparation, analysis, report and drawing conclusion
   2. Sampling, sample preparation, analysis, formulating question, selecting analytical procedure, report and drawing conclusion
   3. Selecting analytical procedure, sampling, sample preparation, analysis, formulating question, report and drawing conclusion
   4. Formulating question, sampling, sample preparation, selecting analytical procedure, analysis, report and drawing conclusion
5. Meso analysis represents particles of what size range?
   1. 10⁻¹ to 1 mm
   2. 10⁻² to 10⁻¹ mm
   3. 10⁻³ to 10⁻² mm
   4. 10⁻⁴ to 10⁻³ mm
6. What is the change in oxidation number of carbon when H₂C₂O₄ changes to CO₂?
   1. +3 to +4
   2. +2 to +1
   3. -3 to -4
   4. -2 to -1
7. What color change do bromocresol green and bromothymol blue show in acidic medium respectively?
   1. pink, colorless
   2. red, blue
   3. yellow, yellow
   4. blue, green
8. Which indicator changes from pink in basic medium to colorless in acidic medium?
   1. phenolphthalein
   2. methyl orange
   3. methyl red
   4. bromothymol blue
9. How many significant figures are in 0.0036?
   1. 1
   2. 2
   3. 3
   4. 4
10. Which of these is not a determinate error?
    1. operative error
    2. methodic error
    3. instrumental error
    4. constant error
11. Which of these methods has the greatest precision?
    1. gravimetric analysis
    2. volumetric analysis
    3. precipitation titration
    4. complexometric titration
12. What is the basis of redox titrimetry?
    1. To measure pH changes during reaction
    2. To know how equivalent weight of reagent is related to its molecular weight
    3. To determine complex formation constants
    4. To measure solubility products
13. What is reduction in chemical terms?
    1. Removal of oxygen or the addition of hydrogen
    2. Removal of hydrogen through oxygen
    3. Addition of O₂
    4. Removal of oxygen through hydrogen
14. Calculate the equivalent weight of H₂C₂O₄·2H₂O when it changes to CO₂ (MW=126 g/mol)
    1. 63 g/equiv
    2. 42 g/equiv
    3. 126 g/equiv
    4. 84 g/equiv
15. When the number of donor groups in a single ligand is 2, it is said to be
    1. monodentate
    2. bidentate
    3. tridentate
    4. polydentate
16. Which of these is not a type of solution?
    1. Colloidal solution
    2. True solution
    3. Precipitate solution
    4. Suspension
17. Is the solute always the solid part in a solution?
    1. True
    2. False
    3. Only in aqueous solutions
    4. Only in organic solutions
18. KMnO₄ reacts with dilute acid to give MnO₂. Is this an example of oxidation?
    1. True
    2. False
    3. Only in strong acid
    4. Depends on concentration
19. A saturated solution of AB₂ contains 8.6×10⁻³ moles AB₂ per liter. What is the solubility product?
    1. 1.2×10⁻⁷ mol³dm⁻⁹
    2. 3.6×10⁻⁷ mol³dm⁻⁹
    3. 7.4×10⁻⁷ mol³dm⁻⁹
    4. 2.54×10⁻⁷ mol³dm⁻⁹
20. Indirect determination of [PO₃]³⁻ by precipitating HgCl₂ is an example of
    1. Volatilization method
    2. Precipitation method
    3. Electrogravimetry
    4. Particulate method
21. What is used for back titration in complexometric titration?
    1. GG
    2. Standard magnesium or zinc solution
    3. Calcium solution
    4. Magnesium or Zinc Solution
22. How many bonding sites does EDTA have?
    1. 2 bonding sites
    2. 6 bonding sites
    3. 4 bonding sites
    4. 8 bonding sites
23. What is the useful pH range for Calmagite indicator?
    1. 8.5-11
    2. 9-11
    3. 6-13
    4. 7.5-10.5
24. Why is buffer added during complexometric titration?
    1. To vary the pH of the titrand
    2. To speed up the reaction
    3. To maintain the pH
    4. To make up the titrant
25. What weight of Fe(NO₃)₂ (MW=180 g/mol) is needed to prepare 500ml of 0.02mol/dm³ solution?
    1. 0.72 g
    2. 18 g
    3. 7.2 g
    4. 1.8 g
26. The solubility of Barium Sulphate is 1.05×10⁻³M at 298K. What is its solubility product?
    1. 1.05×10⁻³ mol²dm⁻⁶
    2. 2.10×10⁻⁶ mol²dm⁻⁶
    3. 1.10×10⁻⁶ mol²dm⁻⁶
    4. 1.40×10⁻⁶ mol²dm⁻⁶
27. Match the following indicators with their characteristic reagents: 1. Mohr 2. Fajan 3. Volhard 4. Iodimetry
    1. 1-Q, 2-R, 3-P, 4-S
    2. 1-S, 2-Q, 3-R, 4-P
    3. 1-R, 2-Q, 3-S, 4-P
    4. 1-R, 2-S, 3-Q, 4-P
28. End point determination in Volhard method involves
    1. Filtration
    2. Washing
    3. Fractional precipitation
    4. Masking
29. Chemical analysis concerned with how much of a substance is present in a sample is called
    1. Quantitative analysis
    2. Qualitative analysis
    3. Volumetric analysis
    4. Theory and practice
30. The most precise method of quantitative analysis is
    1. gravimetry
    2. precipitation
    3. redox titration
    4. complexometry
31. Which of the following is an experimental error?
    1. Imprecision of measurements
    2. Wrong measurements
    3. Use of uncalibrated equipment
    4. Human bias
32. The indicator used in Mohr titration is _____
    1. Chromate salt
    2. Fluorescein
    3. Starch solution
    4. Phenolphthalein
33. Which of the following method uses filtration of the AgCl precipitate?
    1. Mohr method
    2. Volhard method
    3. Fajans method
    4. Adsorption method
34. The closeness of values to the true value is ____
    1. Accuracy
    2. Precision
    3. Absolute error
    4. Relative error
35. Oxidation number gives incorrect value of valency.
    1. True
    2. False
    3. Partially true
    4. Depends on the element
36. Hg₂Cl₂ is used in which type of gravimetric analysis?
    1. Precipitation gravimetry
    2. Particulate gravimetry
    3. Electrogravimetry
    4. Thermogravimetry
37. EDTA forms stable complexes with most metal ions. This makes it:
    1. Unselective
    2. Selective
    3. pH-dependent
    4. Redox-sensitive
38. Which of these is not a method for complexometric titration?
    1. Use of masking agent
    2. pH range adjustment
    3. Redox indicator
    4. None of the above
39. Uncertainty in measurements refers to:
    1. Known error
    2. Unknown error
    3. Systematic error
    4. Gross error
40. Which indicator is suitable for CH₃COOH and NH₄OH titration?
    1. Methyl red
    2. Methyl yellow
    3. Phenolphthalein
    4. No suitable indicator
41. Errors in experiments cannot be completely:
    1. Studied
    2. Eliminated
    3. Avoided
    4. Quantified
42. A substance that brings out a precipitate is called a:
    1. Precipitant
    2. Coagulant
    3. Analyte
    4. Catalyst
43. Which indicator is NOT used for HNO₃ and NH₄OH titration?
    1. Methyl red
    2. Methyl orange
    3. Phenolphthalein
    4. Thymol blue
44. In the reaction MnO₄⁻ → Mn²⁺, how many H⁺ and H₂O molecules are required?
    1. 8H⁺ + 4H₂O
    2. 6H⁺ + 3H₂O
    3. 4H⁺ + 2H₂O
    4. 10H⁺ + 5H₂O
45. Coprecipitation refers to:
    1. Precipitation of impurities with the analyte
    2. Selective precipitation
    3. Electrochemical deposition
    4. Colloidal formation
46. Which compound is used to standardize EDTA solutions?
    1. CaCO₃
    2. Na₂CO₃
    3. KHP
    4. AgNO₃
47. How many carboxylic groups are present in EDTA?
    1. 2
    2. 3
    3. 4
    4. 6

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