Title DPP 8 Solutions.pdf ✅

Class : XIIth Subject : CHEMISTRY Date : DPP No. : 8 1 (a) In smelting, powerful reducing agents like C, H2,CO etc are used 2 (b) Calamine is an ore of Zn containing ZnCO3. 3 (c) On striking the electric are between the electrodes, high temperature is produced due to which the charge melts. 4 (d) 2CuO + CuS⟶3Cu + SO2↑ 5 (d) Roasting is mainly used in the extraction of sulphide ores. Galena—PbS, Iron pyrite-FeS, Copper glance-Cu2S . 7 (c) It is a fact. 8 (c) Smelting is a process of reducing metal oxide to metal by means of coke or CO Fe2O3 + 3C→2Fe + 3CO Fe2O3 + 3CO→2Fe + 3CO2 9 (d) Pb, Cu, and Hg all are refined by Oxidation method. 10 (c) Cast iron, wrought iron and steel may be produced from pig iron. 11 (d) Follow text. 12 (a) The abundance ratio : O > Si > Al > Fe . 13 (c) Cuprite (Cu2O) is oxide but argentite (Ag2S) is not oxide 14 (b) To convert ores into oxides and remove Sulphur as volatile SO2. 15 (c) Chile saltpetre is NaNO3 . Topic :- Isolation Elements Solutions
16 (d) Ni(CO)4 ∆ Ni + 4CO 17 (b) Sulphur occurs in native state while iodine, phosphorus and magnesium are found in combined state. 18 (b) Argentite is an ore of Ag having composition Ag2S.It dissolves in NaCN due to formation of soluble complex Ag2S + 4NaCN→2Na[Ag(CN)2 ] + NaCl ∴ NaCN is used to dissolve argentite 19 (c) It is one use of lead. 20 (c) The process of zinc –plating on iron-sheet is known is known as galvanisation
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. A B C D D C C C D C Q. 11 12 13 14 15 16 17 18 19 20 A. D A C B C D B B C C