Tiêu đề DPP 7 Solutions.pdf ✅

Class : XIIth Subject : CHEMISTRY Date : DPP No. : 7 2 (b) Al acts as strong reducing agent and converts many metal oxides (excepts I and II gp) to metals. 3 (b) Cassiterite is an ore of tin. 4 (c) Haematite is an ore of Fe. 5 (d) It is an ore of Mg containing MgCO3 . 6 (c) Combustion zone 1800 K Fusion zone 1600 K Slag zone 1300 K Reduction zone 800 K 7 (d) All minerals are not suitable for the extraction for the extraction of metals commercially. Thus, all ores are minerals, but all minerals are not ores 8 (c) It is a fact. 9 (c) Lepidolite is (Li, K, Na)2 Al2 (SiO3 )3 ∙ (F ∙ OH)2. 10 (c) Au + 3HNO3 + 4HCl⟶HAuCl4 + 3NO2 + 3H2O 11 (b) The slag float over molten mass. 12 (d) Cassiterite is a principal ore of tin containing SnO2. 13 (b) It is a fact. 14 (a) Pyrolusite (MnO2) is not a sulphide ore, so it is not concentrated by forth floatation process Topic :- Isolation Elements Solutions
15 (b) Follow text. 16 (d) Dollucite is caesium aluminium silicate containing about 30% of caesium. 17 (c) Roasting is the process in which the ore is heated strongly below its melting point is presence of air 18 (d) Anglesite is PbSO4. 19 (a) It is a fact. 20 (c) Pine oil reduces the surface tension of water and the solution forms froths.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. D B B C D C D C C C Q. 11 12 13 14 15 16 17 18 19 20 A. B D B A B D C D A C