QUALITY ANALYSIS
QUALITY ANALYSIS
1. On being strongly heated, a blue salt leaves a black residue. Which of the following cations can be present in the salt?
(a) Fe2+ (b) Fe3+
(c) Cu2+ (d) Zn2+
2. A white substance, when strongly heated, leaves a residue which is yellow while hot and white when cold, and gives a gas that turns baryta water milky and acidified dichromate paper green. The substance can be
(a) ZnCO3 (b) ZnSO3
(c) Na2S (d) BaSO3
3. A white crystalline salt imparts a violet colour to a Bunsen flame, and with hot concentrated H2SO4, forms a pungent gas. On treatment with an AgNO3 solution, this gas forms a white precipitate readily soluble in NH3. The white crystalline salt may be
(a) Na2SO4 (b) KCl
(c) CaCl2 (d) SrCl2
4. Which of the following pairs of cations can be separated by using an NaOH solution?
(a) Cu2+, Zn2+ (b) Pb2+, Al3+
(c) Sn2+, Pb2+ (d) Zn2+, Pb2+
5. Which of the following pairs of cations can be separated by using dilute HCl in cold conditions?
(a) Ag+, Cu2+ (b) Ag+,
(c) Ag+, Pb2+ (d) Pb2+,
Answers
1. (c)
2. (b)
ZnO is yellow when it is hot and white when it is cold.
3. (b)
4. (a) Because is white ppt, but Cu(OH)2 is water soluble.
5. (a) AgCl is white ppt.
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