Title DPP-8 SOLUTION.pdf ✅

CLASS : XIth SUBJECT : CHEMISTRY DATE : DPP No. : 8 1 (c) After smelting in blast furnace, the slag is removed from slag hole of the furnace while a molten mass containing mostly Cu2S + little FeS is called matte; it contains 80% metal. 2 (c) There is very small difference in energies of 5f, 6d and 7s orbitals of actinoids, therefore their electronic configuration cannot assigned with a degree of certainty 3 (d) In Mac-Arthur-Forrest method silver is extracted from the solution of sodium argentocyanide by using zinc. 2Na[Ag(CN)2] + Zn⟶Na2[Zn(CN)4] + 2Ag↓ 5 (d) It is Mn and exhibits +7 oxidation state. 6 (d) The size of lanthanides are smaller than expected. This is associated with the filling with the filling up of 4f orbitals which must be filled before the 5d orbitals. The electrons in f- orbitals are not effective in screening other electrons from the nuclear charge 7 (b) Ag + + e⟶Ag ; finely divided Ag is black in colour and thus.AgNO3 causes black stain on skin. It is therefore, called lunar caustic. 8 (a) Due to 3d 5 configuration. 9 (c) Gd = [Xe]4f 7 5d 1 6s 2 , Gd 3+ = [Xe]4f 7 (half-filled) 10 (a) 3Hg + 8HNO3(dil.)⟶3Hg(NO3 )2 + 2NO Soluble and washed away +4H2O 11 (d) E°OP of Hg > E°OP of H. Thus, Hg is less reactive than H2. 12 (a) Brass is an alloy of Cu + Zn (60-80% + 40-20% respectively). Topic :- THE D-AND F-BLOCK ELEMENTS Solutions
13 (a) Maximum number of unpaired electrons are in Mn. 15 (d) It is a use of Ti alloys. 16 (c) Ore Chemical composition Cuprite Cu2O Chalcocite Cu2S Chalcopyrite CuFeS2 Malachite Cu(OH)2.CuCO3 In these ores, chalcopyrite (CuFeS2) Contains both iron and copper. 17 (c) Potassium dichromate, on heating give oxygen and chromic oxide (Cr2O3 ) 4K2Cr2O7 ∆ 4K2Cr2O4 + 3O2 + 2Cr2O3 18 (b) 3KCNS + FeCl3⟶3KCl + Fe(CNS)3. Blood ― red colour 19 (a) Fe, Co, Ni are called ferrous metals. 20 (d) Ag + + e⟶Ag, i.e, Ag + is reduced.
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. C C D A D D B A C A Q. 11 12 13 14 15 16 17 18 19 20 A. D A A A D C C B A D