Title DPP-3 SOLUTION.pdf ✅

CLASS : XIth SUBJECT : CHEMISTRY DATE : DPP No. : 3 1 (b) HgO ∆ Hg + 1 2 O2 2 (a) Cast iron has the highest percentage of carbon. It contains 2 to 4.5 % of carbon along with impurities such as sulphur, silicon, phosphorus etc. It is the least pure form of iron. 3 (a) Argentite is Ag2S. 4 (d) 2HgS + 3O2⟶2HgO + 2SO2, 2HgO + HgS⟶3Hg + SO2 5 (a) Transuranic elements start after uranium and begin with Np (Neptunium) 6 (a) All these compounds are less soluble in water and only Zn(OH)2 is soluble in NH4Cl + NH4 OH due to formation of tetramine zinc (II) complex. Zn2+ + 4NH4OH⟶[Zn(NH3 )4 ] 2+ + 2H2O 7 (d) Transition metals can form ionic or covalent compounds and their melting and boiling points are high. Their compounds are generally coloured and they usually exhibit variable valency. 8 (b) Both KMnO4 and FeCl3 are oxidant and thus, no reaction. 9 (b) Alloy is a homogeneous mixture of two or more metals. Mercury forms amalgams (alloy) with gold, silver and tin. But it does not react with iron or platinum. 10 (b) Purple of Cassius is the trade name for gold sol. in water. 12 (d) Gd(64) Topic :- THE D-AND F-BLOCK ELEMENTS Solutions
[Xe]54 4f 7 ↑ ↑ ↑ ↑ ↑ ↑ ↑ 5d 1 ↑ ⥮ All the electrons of 4f-orbital are unpaired, hence stable. Thus, Gd(64) has EC as [Xe]54 4f 7 5d 1 6s 2 Instead of [Xe]54 4f 8 6s 2 13 (c) The electronic configuration of mercury (80) is [Xe]4f 10, 5d 10,6s 2 . Its d-subshell is completely filled, thus it prevents the overlapping of d-orbitals (d ― d overlapping). Hence, it is liquid metal at room temperature. 14 (c) Azurite is the ore of copper, its molecular formula is Cu(OH)2.2CuCO3. 15 (b) CrO2― 4 + 2H + ⟶Cr2O 2― 7 + H2O 16 (d) Zn + 2HCl⟶ZnCl2 + H2 Zn + H2SO4 Dil. ⟶ZnSO4 + H2 4Zn + 10HNO3⟶4Zn(NO3 )2 + N2O + 5H2O Thus, NO― 3 ions are reduced to N2O whereas in first two reactions H + is reduced to H2. 17 (b) Siderite —FeCO3, calcite (or limestone) — CaCO3, silver glance(or argentite) —Ag2S, fool’s gold (or iron pyrites) —FeS2. 18 (c) 3Fe + 4H2O⟶Fe3O4 + 4H2 19 (d) In the electrolytic refining of zinc, anode is made up of impure zinc while a strip of pure zinc acts as cathode. An acidified solution of zinc sulphate acts as electrolyte. When electricity is passed, following reactions occur. At cathode Zn2+ + 2e ―⟶Zn pure At anode Zn⟶ Zn2+ + 2e ― impure
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. B A A D A A D B B B Q. 11 12 13 14 15 16 17 18 19 20 A. C D C C B D B C D B