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Lesson 2 – Chemical Analysis and Qualitative Separation of Anions and Cations — Lesson quiz

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  • Questions count: 10
  • Passing grade: 60%
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1.
When dilute hydrochloric acid is added to a solid salt, a gas is evolved with a pungent odor that turns acidified potassium dichromate paper green while a colloidal yellow precipitate of sulfur separates in the reaction vessel. The anion is:
Thiosulfate (S₂O₃2-)
Sulfite (SO₃2-)
Sulfide (S2-)
Sulfate (SO₄2-)
2.
To distinguish between a white precipitate of barium sulfate (BaSO₄) and a white precipitate of barium phosphate (Ba₃(PO₄)₂), one should add:
Boiling distilled water
Ammonium hydroxide solution
Dilute hydrochloric acid (Ba₃(PO₄)₂ dissolves while BaSO₄ remains insoluble)
Concentrated nitric acid in the dark
3.
A metal cation that forms a gelatinous white precipitate with NaOH which completely redissolves in excess reagent to form a soluble clear solution is:
Al3+ (due to the formation of soluble sodium meta-aluminate NaAlO₂)
Fe2+
Fe3+
Ca2+
4.
In a titration experiment, 20.0 mL of 0.15 M H₂SO₄ is completely neutralized by 30.0 mL of NaOH solution. The molar concentration of the NaOH solution is:
0.10 M
0.20 M
0.05 M
0.30 M
5.
The indicator that exhibits a yellow color in acidic medium, blue in alkaline medium, and green in neutral medium is:
Methyl orange
Litmus solution
Phenolphthalein
Bromothymol blue
6.
When dilute hydrochloric acid is added to a solid salt, a gas is evolved with a pungent odor that turns acidified potassium dichromate paper green while a colloidal yellow precipitate of sulfur separates in the reaction vessel. The anion is:
Thiosulfate (S₂O₃2-)
Sulfite (SO₃2-)
Sulfide (S2-)
Sulfate (SO₄2-)
7.
To distinguish between a white precipitate of barium sulfate (BaSO₄) and a white precipitate of barium phosphate (Ba₃(PO₄)₂), one should add:
Boiling distilled water
Ammonium hydroxide solution
Dilute hydrochloric acid (Ba₃(PO₄)₂ dissolves while BaSO₄ remains insoluble)
Concentrated nitric acid in the dark
8.
A metal cation that forms a gelatinous white precipitate with NaOH which completely redissolves in excess reagent to form a soluble clear solution is:
Al3+ (due to the formation of soluble sodium meta-aluminate NaAlO₂)
Fe2+
Fe3+
Ca2+
9.
In a titration experiment, 20.0 mL of 0.15 M H₂SO₄ is completely neutralized by 30.0 mL of NaOH solution. The molar concentration of the NaOH solution is:
0.10 M
0.20 M
0.05 M
0.30 M
10.
The indicator that exhibits a yellow color in acidic medium, blue in alkaline medium, and green in neutral medium is:
Methyl orange
Litmus solution
Phenolphthalein
Bromothymol blue
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