Qualitative Analysis Self Test
Self test on observations of Qualitative Analysis.
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- 1.
Which of the following ions in solution would form a reddish-brown precipitate when aqueous sodium hydroxide solution is added dropwise to it?
- A.
Copper(II) ions
- B.
Iron(II) ions
- C.
Iron(III) ions
- D.
Zinc ions
Correct Answer
C. Iron(III) ionsExplanation
Iron(III) ions would form a reddish-brown precipitate when aqueous sodium hydroxide solution is added dropwise to it. This is because iron(III) ions react with sodium hydroxide to form iron(III) hydroxide, which is a reddish-brown precipitate. Copper(II) ions do not form a reddish-brown precipitate, but rather a blue precipitate. Iron(II) ions and zinc ions do not form precipitates with sodium hydroxide.Rate this question:
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- 2.
Which of the following ions in solution would form a white precipitate that is soluble in excess sodium hydroxide solution is added to it?
- A.
Aluminium ions
- B.
Calcium ions
- C.
Lead(II) ions
- D.
Zinc ions
Correct Answer(s)
A. Aluminium ions
C. Lead(II) ions
D. Zinc ionsExplanation
Aluminium ions, Lead(II) ions, and Zinc ions would form a white precipitate that is soluble in excess sodium hydroxide solution. This is because these ions can react with sodium hydroxide to form their respective hydroxide compounds, which are white precipitates. However, these precipitates are soluble in excess sodium hydroxide solution due to the formation of soluble complex ions.Rate this question:
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- 3.
Which of the following ions in solution would form a white precipitate when acidified barium nitrate solution is added to it?
- A.
Chloride ion
- B.
Iodide ion
- C.
Nitrate ion
- D.
Sulfate ion
Correct Answer
D. Sulfate ionExplanation
When acidified barium nitrate solution is added to sulfate ions in solution, a white precipitate of barium sulfate is formed. This is because barium sulfate is insoluble in water and forms a solid precipitate when barium ions react with sulfate ions.Rate this question:
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- 4.
Which of the following gases fits the following description?"The gas is colourless, pungent and turns moist blue litmus paper pink and bleaches it."
- A.
Ammonia
- B.
Chlorine
- C.
Oxygen
- D.
Sulfur dioxide
Correct Answer(s)
B. Chlorine
D. Sulfur dioxideExplanation
Chlorine and sulfur dioxide are the correct answers because both gases are colorless and have a pungent odor. Additionally, they both have the ability to turn moist blue litmus paper pink and bleach it.Rate this question:
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- 5.
What would be the observations when aqueous ammonia is added to a solution of zinc nitrate (until in excess) and heated?
- A.
White precipitate formed. On heating, a colourless, pungent gas evolved.
- B.
White precipitate formed which dissolved in excess aqeous ammonia to form a colourless solution.
- C.
White precipitate formed which dissolved in excess aqeous ammonia to form a colourless solution. On heating, a colourless, pungent gas evolved.
- D.
Blue precipitate formed which dissolved in excess aqeous ammonia to form a dark blue solution. On heating, a colourless, pungent gas evolved.
Correct Answer
C. White precipitate formed which dissolved in excess aqeous ammonia to form a colourless solution. On heating, a colourless, pungent gas evolved.Explanation
When aqueous ammonia is added to a solution of zinc nitrate until in excess and heated, a white precipitate is formed. This white precipitate is zinc hydroxide, which is insoluble in water. However, when excess aqueous ammonia is added, it dissolves the white precipitate to form a colorless solution. This is because zinc hydroxide reacts with excess aqueous ammonia to form a complex ion called tetraamminezinc(II) ion, which is soluble in water. On heating, a colorless and pungent gas, which is ammonia gas, is evolved due to the decomposition of the tetraamminezinc(II) ion.Rate this question:
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Mar 21, 2023Quiz Edited by
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Feb 26, 2010Quiz Created by
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