Chemistry
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New answer posted
a year agoContributor-Level 10
55. (ii) Both assertion and reason are true but reason is not the correct explanation of assertion.
Explanation: Hydrometallurgy is used to extract copper from low-grade ore. Hydrometallurgy entails dissolving the ore in a suitable reagent and then precipitating it. In this method, more electropositive metal is used, allowing pure metal to be displaced.
New answer posted
a year agoContributor-Level 10
36. (A)i, ii
Disproportionation/redox reaction is a reaction in which one compound is oxidised as well as reduced at the same time.
(A) Cu+ ? Cu2+ + Cu
( + 1) ( + 2) (0)
(B) 3MnO4- + 4H+ ? 2MnO4- + MnO2 + 2H2O
( + 6) ( + 7) ( + 4)
New answer posted
a year 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
a year agoContributor-Level 10
35. (B)+3
Out of all +3 is the most common oxidation state for all the lanthanide elements.
New answer posted
a year 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
a year agoContributor-Level 10
34. (B) 3d5
Magnetic moment of an electron/dipole moment is caused by its intrinsic properties of spin and electric charge. It depends upon the number of unpaired electrons in its valence shell. The more the number of unpaired electrons, the greater will be the value of magnetic moment.
3d7 = 3 unpaired electrons
3d5 = 5 unpaired electrons
3d8 = 2 unpaired electrons
3d2 = 2 unpaired electrons
Out of all, 3d5 has five unpaired electrons that is maximum and hence it has the highest magnetic moment.
New answer posted
a year 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
a year 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
a year agoContributor-Level 10
33. (A) Mn2O7
2KMnO4 + 2H2SO4 (conc.) → Mn2O7 + 2KHSO4 + H2O
Manganese heptoxide is an acid anhydride of permanganic acid ( HMnO4). It is a dangerous oxidiser, volatile and highly reactive liquid.
New answer posted
a year 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
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