Tiêu đề DPP 4 Solutions.pdf ✅

Class : XIIth Subject : CHEMISTRY Date : DPP No. : 4 1 (c) Kiesserite is an ore of Mg containing, MgSO4 ∙ H2O . 2 (a) In smelting carbon is used for the reduction of oxide to metal. 3 (c) Metallic character increases down the gp. 4 (d) Ag, Au are obtained by complex formation. 5 (c) Diamond consists of carbon atoms only. 6 (d) Impurities are known as matrix or gangue. 7 (c) CaCN2 is used as a fertilizer. 8 (c) It is a fact. 9 (b) It is found in human body as haemoglobin. 10 (d) Flux is used to fuse non-fusible impurities (both acidic and basic) present in the ore 11 (d) Flux is a substance with combine with gangue that present in the roasted or calcined ore to form fusible product, called slag 12 (a) Oxides of less electropositive metals such as Cr2O3,Mn etc are reduced by using Al. This process is called them process Cr2O3 + 2Al→Al2O3 + 2Cr + Head 13 (a) Gangue particles are wetted up by water and adsorbed. 14 (d) Composition of various alloy of steels are as-Nickel steel -3.5% Ni, Chrome steel-1.5-2% Cr, Chrome-vanadium -0.15% V, I % Cr, Manganese steel-1.2-15% Mn, Tungsten steel 14-20% W, 3-8% Cr, Invar 36% Ni, Stainless steel 11.5% Cr. Topic :- Isolation Elements Solutions
15 (b) Leaching is used to make insoluble ore in soluble form. 16 (d) In electroefining of copper, some gold is deposited as anode mud 17 (c) Thus, furnace material can withstand high temperature. 18 (d) Anode : Cu⟶Cu 2+ + 2e (Impure sample) Cathode : Cu 2+ +2e⟶Cu (Pure Cu) 19 (c) Ag2S forms soluble complex with KCN. 20 (a) Van-Arkel method is used to purify metals such asZr, Ti, V, Th, etc, limestone is basic flux. Dolomite (CaCO3) is an ore of Ca. Willemite (Zn2SiO4) is a silicate ore
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. C A C D C D C C B D Q. 11 12 13 14 15 16 17 18 19 20 A. D A A D B D C D C A