Chemistry NCERT Exemplar Solutions Class 12th Chapter Six
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4 months agoContributor-Level 10
54. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion.
Explanation: The zone refining method is very useful for producing high-purity semiconductors and other metals, such as germanium.
New answer posted
4 months agoContributor-Level 10
53. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion.
Explanation: Froth Flotation method is used to separate the hydrophobic materials from hydrophilic materials. In this method a mixture of palm oil, water and detergent is taken in a tank along with powdered sulfide ore. Compressed air is then passed through the pipe of the rotating agitator to create froth. The sulfide ore is then wetted by the palm oil mixture and it rises with the froth and the impurities or gauge settles at the bottom of the tank. The froth containing the sulfide is then cleaned and dried. Cresols or Aniline
New answer posted
4 months agoContributor-Level 10
52. (i) Both assertion and reason are true and reason is the correct explanation of assertion.
Explanation: Van Arkel method is generally used to obtain pure forms of Zirconium (Zr) and Titanium (Ti).
The metal iodide is heated at 1800 K and is decomposed on a tungsten filament. The pure metal is dropped on the tungsten filament. This proves that ZrI4 is volatile and decomposes at 1800 K.
New answer posted
4 months agoContributor-Level 10
51. (i) Both assertion and reason are true and reason is the correct explanation of assertion.
Explanation: In the Mond process Nickel is reacted with carbon monoxide reversibly to give Nickel carbonyl, Ni (CO)4. Nickel carbonyl is a volatile compound. It decomposes to nickel and carbon monoxide at 460 K.
New answer posted
4 months agoContributor-Level 10
50. Option (i) A (2) B (3) C (4) D (1)
Explanation: A solidified copper has a blistered appearance due to the evolution of SO2 Hence it is called blistered copper.
Hence, option (A) from column I is matched with option (2) from column II. Iron is extracted from a blast furnace.
Hence, option (B) from column I is matched with option (3) from column II. The iron ore is heated in the reverberatory furnace after mixing with silica. In the furnace, iron oxide slags of iron and copper are produced in the form of copper matte.
Hence, option (C) from column I is matched with option (4) from column II. The hall-Heroult process is used for the extra
New answer posted
4 months agoContributor-Level 10
49. Option (i) A (3) B (4) C (2) D (1)
Sapphire is a gemstone containing Co.
Hence, option (A) from column I is matched with option (3) from column II. The Sphalerite single is ZnS.
Hence, option (B) from column I is matched with option (4) from column II. NaCN is also used as a depressant.
Hence, option (C) from column I is matched with option (2) from column II. Al2O3 is also called corundum.
Hence, option (D) from column I is matched with option (1) from column II.
New answer posted
4 months agoContributor-Level 10
48. Correct code (i) A (4) B (2) C (3) D (1)
The cyanide process is used in the extraction of Au.
Hence, option (A) from column I is matched with option (4) from column II. Froth floatation process is used in the dressing of ZnS.
Hence, option (B) from column I is matched with option (2) from column II. Electrolytic reduction is used in the extraction of AI.
Hence, option (C) from column I is matched with option (3) from column II. Zone refining is used to get ultrapure Ge.
Hence, option (D) from column I is matched with option (1) from column II.
New answer posted
4 months agoContributor-Level 10
47. Option (ii) A (4) B (3) C (1) D (2)
Coloured bands are found in chromatography.
Hence, option (A) from column I is matched with option (4) from column II. Impure metals are converted to volatile complexes in Mond's process.
Hence, option (B) from column I is matched with option (3) from column II. Purification of Ge and silicon is done using zone refining.
Hence, option (C) from column I is matched with option (1) from column II. Purification of mercury is done using fractional distillation.
Hence, option (D) from column I is matched with option (2) from column II.
New answer posted
4 months agoContributor-Level 10
46. Option (ii) A (2) B (4) C (5) D (3)
Pendulum is always made of nickel steel.
Hence, option (A) from column I is matched with option (2) from column II. Malachite is the ore of copper.
Hence, option (B) from column I is matched with option (4) from column II. Calamine is the ore of zinc.
Hence, option (C) from column I is matched with option (5) from column II. Cryolite is an ore of aluminum.
Hence, option (D) from column I is matched with option (3) from column II.
New answer posted
4 months agoContributor-Level 10
45. Option (ii) and (iii)
Explanation: Using oxidation method for extraction of chlorine from brine. The reactions involved are:
2Cl− + 2H2O → 2OH− + H2 + Cl2
For this reaction, the value of ΔG°=+422 kJ, which is positive. Using the formula ΔG°=−nE°F, we get a negative value of E° =−2.2 V.
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