Tiêu đề DPP 1 Solutions.pdf ✅

Class : XIIth Subject : CHEMISTRY Date : DPP No. : 1 1 (d) Calcination involves decomposition of ore to remove volatile impurities. 2 (a) FeO + SiO2⟶FeSiO3 (Fusible slag) Cu2O + FeS⟶Cu2S + FeO Slag is removed from the slag hole while a molten mass containing mostly cuprous sulphide with a little ferrous sulphide called matte. 3 (b) Mond’s process is used for the purification of Ni. 4 (c) It is a fact. 5 (b) Bauxite (Al2O3.2H2O) Corundum (Al2O3 ) Diaspore (Al2O3.H2O) 6 (b) Extraction of less electropositive metals say Cr, Mn, Cu, Ca, Ni, etc., can be done by heating their oxides with strong reducing agents, e.g., CO, CO + H + Na, Al, Mg, etc. 7 (a) Lead extracted from argentiferrous galena contains small quantities of silver. Recovery of silver from argentiferrous lead is an economical proposition and is carried out by Parke’s process. 8 (b) Oxygen family is known as chalcogens. 9 (a) Apatite is CaF2.3Ca3 (pO4 )2 ∴ It is ore of fluorine with calcium 10 (d) A bronze sulphide mineral (Fe,Ni)9S8, a chief ore of Ni. 11 (a) Pitch blende is an ore of uranium containing U3O8. 12 (a) In alumino-thermic process, aluminium is used as reducing agent Topic :- Isolation Elements Solutions
13 (a) ___do____ 14 (a) The adsorption phenomenon is involved in the forth floatation process 15 (c) It is a fact. 16 (a) Stainless steel is an alloy of iron with chromium and nicl Its composition is 82% Fe and 18% (Cr+Ni). It res corrosion and used for making automobile parts and utensils 17 (d) It is a fact. 18 (d) Cyanide process is used in the extraction of both silver and gold because these form complex salts with CN ― ion due to presence of lone pair of electron on nitrogen atom 19 (d) All are characteristic features of alloy. 20 (d) All are noble metals.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. D A B C B B A B A D Q. 11 12 13 14 15 16 17 18 19 20 A. A A A A C A D D D D