Qualitative Analysis
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A solid X has the following properties. (i) It is insoluble in water (ii) It gives off a gas when heated. (iii) It gives a gas when added to dilute sulfuric acid. Which one of the following could X be?
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Calcium hydroxide
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Copper (II) carbonate
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Sodium carbonate
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Zinc oxide
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- 2.
A pale green solution X gives a green precipitate with excess aqueous sodium hydroxide. An alkaline gas is only given off when the mixture is warmed with powdered aluminum. Which ion does X contain?
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Ammonium and copper(II)
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Ammonium and iron (III)
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Copper (II) and nitrate
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Iron (II) and nitrate
Correct Answer
A. Iron (II) and nitrateExplanation
Pale green solution: Iron(II) ions (Fe²⁺) in solution often appear pale green.
Green precipitate with excess aqueous sodium hydroxide: Iron(II) hydroxide, Fe(OH)₂, forms a green precipitate when iron(II) ions react with sodium hydroxide.
Alkaline gas given off when warmed with powdered aluminum: This indicates the presence of nitrate ions (NO₃⁻). When nitrates are warmed with powdered aluminum in an alkaline solution, ammonia gas (NH₃) is released.Rate this question:
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- 3.
What reaction occurs when aqueous copper (II) sulfate is added to aqueous sodium hydroxide?
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Displacement
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Redox
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Precipitation
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Neutralisation
Correct Answer
A. PrecipitationExplanation
When aqueous copper (II) sulfate is added to aqueous sodium hydroxide, a precipitation reaction occurs. This means that a solid substance, called a precipitate, is formed. In this case, the precipitate formed is copper (II) hydroxide, which is insoluble in water. The reaction can be represented by the following equation: CuSO4 (aq) + 2NaOH (aq) → Cu(OH)2 (s) + Na2SO4 (aq).Rate this question:
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- 4.
Two bottles in a laboratory are unlabelled. One bottle is known to contain aqueous sodium iodide and the other aqueous sodium chloride. What test would identify the solutions?
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Adition of aqueous lead (II) nitrate
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Addition of dilute sulfuric acid
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Addition of blue litmus paper.
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Addition of sodium hydroxide
Correct Answer
A. Adition of aqueous lead (II) nitrateExplanation
Adding aqueous lead (II) nitrate to the solutions would identify the solutions. This is because when lead (II) nitrate is added to a solution containing iodide ions (such as the one with aqueous sodium iodide), a yellow precipitate of lead (II) iodide is formed. On the other hand, if lead (II) nitrate is added to a solution containing chloride ions (such as the one with aqueous sodium chloride), a white precipitate of lead (II) chloride is formed. Therefore, by observing the color of the precipitate formed, we can identify which solution contains sodium iodide and which contains sodium chloride.Rate this question:
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- 5.
Which of the following CANNOT be used to distinguish between aqueous lead (II) nitrate and aqueous aluminium nitrate?
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Dilute hydrochloric acid
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Dilute sulfuric acid
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Aqueous potassium iodide
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Aqueous sodium hydroxide
Correct Answer
A. Aqueous sodium hydroxideExplanation
Aqueous sodium hydroxide cannot be used to distinguish between aqueous lead (II) nitrate and aqueous aluminium nitrate because both lead (II) nitrate and aluminium nitrate will form white precipitates when reacted with aqueous sodium hydroxide. Therefore, this test will not provide a reliable distinction between the two compounds.Rate this question:
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- 6.
Which of the following pairs of solutions give a white precipitate when mixed?
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Sodium chloride and lead (II) nitrate
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Barium nitrate and calcium chloride
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Iron (II) chloride and sodium hydroxide
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Sodium sulfate and aluminium chloride
Correct Answer
A. Sodium chloride and lead (II) nitrateExplanation
When sodium chloride and lead (II) nitrate are mixed, a white precipitate of lead chloride is formed. This is because lead chloride is insoluble in water and therefore forms a solid precipitate.Rate this question:
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- 7.
Which two gases each change the colour of damp blue litmus paper?
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Ammonia and chlorine
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Oxygen and hydrogen chloride
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Carbon dioxide and hydrogen
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Carbon dioxide and chlorine
Correct Answer
A. Carbon dioxide and chlorineExplanation
Carbon dioxide and chlorine are the two gases that change the color of damp blue litmus paper. Carbon dioxide turns the litmus paper pink, indicating acidity, while chlorine turns it white, indicating the presence of a strong oxidizing agent.Rate this question:
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- 8.
Dilute HCl was added to a tube containing an unknown powder. The powder dissolved with no effervescence observed. After the reaction stopped, excess aqueous sodium hydroxide was added to the tube and a white precipitate formed. What was the unknown powder?
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Zinc oxide
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Lead (II) oxide
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Calcium oxide
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Calcium carbonate
Correct Answer
A. Calcium oxideExplanation
The correct answer is calcium oxide. When dilute HCl is added to calcium oxide, it reacts to form calcium chloride and water. This reaction does not produce any gas, so no effervescence is observed. When excess aqueous sodium hydroxide is added to the tube, it reacts with the remaining calcium chloride to form calcium hydroxide, which is insoluble in water and appears as a white precipitate. This confirms that the unknown powder was calcium oxide.Rate this question:
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- 9.
Under suitable conditions, dilute HCl reacts with each of the following substances. Which reaction gives a colourless solution only?
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Aqueous silver nitrate
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Calcium carbonate
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Copper (II) oxide
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Limewater
Correct Answer
A. LimewaterExplanation
Limewater is the only substance among the options that gives a colorless solution when reacted with dilute HCl. Aqueous silver nitrate produces a white precipitate of silver chloride, calcium carbonate reacts to form a white precipitate of calcium chloride, copper (II) oxide forms a blue solution due to the formation of copper chloride, while limewater reacts with HCl to form calcium chloride, which remains in solution and does not produce any visible color change.Rate this question:
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- 10.
Excess barium nitrate is added to dilute sulfuric acid. The precipitate formed is removed by filtration. What ions are present in the filtrate?
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Ba2+ and NO3-
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Ba2+, H+ and NO3-
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H+ and NO3-
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H+, NO3- and SO42-
Correct Answer
A. Ba2+, H+ and NO3-Explanation
When excess barium nitrate is added to dilute sulfuric acid, a reaction occurs between the barium nitrate and sulfuric acid, resulting in the formation of a precipitate. The precipitate is then removed by filtration, leaving behind the ions that were present in the filtrate. Since barium nitrate is a salt composed of Ba2+ and NO3- ions, and sulfuric acid is an acid composed of H+ and SO42- ions, the ions present in the filtrate would be Ba2+, H+, and NO3-.Rate this question:
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Current Version
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Jul 12, 2024Quiz Edited by
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May 14, 2010Quiz Created by
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