Transition Elements Exercise # 3

TRANSITION ELEMENTS Exercise # 3 1. [Matrix Match Type Questions] Part # I Match the reactions listed in Column () with the characteristic(s) of the products/type of reactions listed in Column (II). Column - I Column - II 2– (A) MnO4 + CO2  (p) Two pungent smelling gases are liberated. (B) CrO42– + H+  (q) Show disproportionation reaction.  (C) FeSO4  (r) Dimeric bridged tetrahedral metal ion.  (D) CuCI2 2H2O  (s) One of the products has central metal in its highest stable oxidation state. 2. Match the salts/mixtures listed in Column () with their respective name listed in Column (II). Column - I Column - II (A) ZnS + BaSO4 mixture (p) Lunar caustic (B) FeSO4 (NH4)2SO4. 6H2O (q) Schwitzer`s regent. (C) AgNO3 (r) Lithopone (D) [Cu(NH3)4]SO4 (s) Mohr's salt 3. Match the pairs of complexes/compounds listed in Column () with the characteristic(s) of the reaction products listed in Column (II). Column - I Column - II (A) Cu(I) and Zn (II) complexes (p) Pair of compounds having similar colour and some magnetic moment but equal. (B) KMnO4 and K2Cr2O7 (q) Pair of compounds which are diamagnetic but coloured. (C) Cu2O and HgI2 (r) Pair of compounds having metals in the highest stable oxidation states. (D) VOCI2 and CuCI2 (s) Pair of compounds which show diamagnetism and are colourless. 4. Column-I (Metals) Column-II (Ores) (A) Zn (p) Cyanide process (B) Cu (q) hydrometallurgical process (C) Ag (r) roasting (D) Pt (s) brass. Column-I (Alloys) (A) TiCl4 Column-II (Constituents) (p) Adams catalyst in reduction (B) PdCl2 (q) In preparation of (CH3)2 SiCl2 (C) Pt/PtO (r) Used as the Natta catalyst in polythene production (D) Cu (s) Wake process for converting C2H4 to CH3CHO 5. 6. Match the reactions in Column I with the types of products / the use of products in Column II. Column - I (A) HO OH + AgBr(s)  Column - II (p) Turnbull’s blue pigment (B) BaCl2 + K2Cr2O7 + H2SO4  (C) FeSO4 + K3[Fe(CN)6]  (D) Cu(OH)2 + NH4OH + (NH4)2SO4  (q) Schwitzer’s reagent (r) Rinmann’s green pigment (s) Chromyl chloride test  (E) ZnO + Co(NO3)2  (t) Photography 7. Match the reactions in Column I with nature of the reactions/type of the products in Column II. Column I Column II    (A) FeSO4 (p) One of the products is coloured due to charge transfer (B) Mn2+ + S2O82– + H2O  (q) One of the products is in + VI oxidation state (C) Na2Cr2O7 + H2SO4(conc.) (saturated solution) (r) Redox reaction (D) N2H4 + CuSO4  (s) One of the products is acidic oxide 8. Match the properties given in Column I with the transition elements given in Column II. Column I Column II (Property) (Transition elements) (A) Highest oxidation state. (p) Cr. (B) Highest density. (q) Os. (C) Element with maximum unpaired electrons. (r) Tc. (D) Radioactive transition element. (s) Ru. 9. Match the transition element ions given in Column I with the characteristic(s) of products given in Column II. Column I Column II (A) Cu2+ . (p) Form amphoteric oxide. (B) Zn2+ . (q) Diamagnetic and colourless compounds. (C) Cr3+. (r)) Coloured hydrated transition metal ion. (D) Ni2+. (s) Paramagnetic. Part # II [Comprehension Type Questions] Comprehension # 1 (i) A powdered substance (A) on treatment with fusion mixture gives a green coloured compound (B). (ii) The solution of (B) in boiling water on acidification with dilute H2SO4 gives a pink coloured compound (C) and brown colour compound (D). (iii) The aqueous solution of (A) on treatment with NaOH and Br2–water gives the compound (D). (iv) A solution of (D) in concentrated HNO3 on treatment with lead peroxide at boiling temperature produced a compound (E) which was of the same colour at that of (C). (v) A solution of (A) on treatment with a solution of barium chloride gave a white precipitate of compound (F) which was insoluble in concentrated HNO3 and concentrated HCl. 1. Which of the following is true for compound (C) ? (A) It oxidises ammonia to nitrogen dioxide in neutral medium. (B) It's pink colour is due to d-d transition. (C) It can be oxidised by ozone. (D) It is obtained by alkaline fusion of pyrolusite followed by electrolytic oxidation. 2. The oxidation state of central metal ions of (A), (B) and (C) compounds are respectively : (A) +II , + VI and + VII (B) +II , + VI and + VI (C) +II , + VII and + VII (D) +VI , + VII and + VII 3. Consider the following statements ; (I) anions of both (B) and (C) are diamagnetic and have tetrahedral geometry. (II) anions of both (B) and (C) are paramagnetic and have tetrahedral geometry. (III) anion of (B) is paramagnetic and that of (C) is diamagnetic but both have tetrahedral geometry. (IV) green coloured compound (B) in a neutral or acidic medium disproportionates to give (C) and (D). of these select the correct one from the codes given : (A) I and III only (B) II and III only (C) II and IV only (D) III and IV only TRANSITION ELEMENTS Comprehension # 2 Paramagnetism is a property due to the presence of unpaired electrons. In case of transition metals, as they contain unpaired electrons in the (n – 1) d orbitals, most of the transition metal ions and their compounds are paramagnetic. Paramagnetism increases with increases in number of unpaired electrons. Magnetic moment is calculated from ‘Spin only formula’ viz. = n (n + 2) B.M n = number of unpaired electrons Similarly the colour of the compounds of transition metals may be attributed to the presence of incomplete (n–1)d sub-shell. When an electron from a lower energy of d-orbital is excited to a higher energy d-orbital, the energy of excitation corresponds to the frequency of light absorbed. This frequency generally lies in the visible region. The colour observed corresponds to complementary colour of the light absorbed. The frequency of the light absorbed is determined by the nature of the ligand. 1. Which of the following pair of compounds is expected to exhibit same colour in aqueous solution. (A) FeCl2 , CuCl2 (B) VOCl2 , CuCl2 (C) VOCl2 , FeCl2 (D) FeCl2 , MnCl2 2. Titanium shows magnetic moment of 1.73 BM in its compound. What is the oxidation state of titanium in the compound ? (A) +2 (B) +1 (C) +3 (D) +4 3. The colourless species is : (A) VCl3 (B) VOSO4 4. (C) Na3VO4 (D) [V(H2O)5SO4]2H2O Identify the incorrect statement. (A) Mn2+ has the highest paramagnetism amongst the bivalent cations of the Ist transition series. (B) The coloured ions or compounds of transition elements are due to d-d transition and charge transfer spectrum. (C) In 3 d series the paramagnetic character first increase to maximum & then starts decreasing. (D) None of these Comprehension # 3 Transition metals usually form coloured complexes and d – d transitions (t2g eg) are responsible for colour as the energy difference between t2g and eg lies in visible region. But all the coloured ions are not due to d–d transition but charge transfer bands also play important roles. Charge transfer bands may be of two types. (i) ligand to metal (CTLM) (ii) metal to ligand (CTML). Charge transfer transition always produces intense colour as compared to d-d transition. 1. Select the incorrect statement : (A) d-block metal ions are usually coloured. (B) Colour of the most of d-block metal ions is generally due to d-d transition. (C) All the complexes of Cu+ are colourless on account of diamagnetic nature i.e. d10 configuration. (D) CrO3 is bright orange due to CTLM. 2. MnO4– is dark purple coloured although Mn is in (+ VII) oxidation state with 3dº configuration : (A) due to d-d transition. (B) due to CTML spectra. (C) due to CTLM spectra (D) none of these. 3. Select the correct statement. (A) In CTML, no net reduction-oxidation takes place because of the short life time of excited state. (B) Cu2O is a red coloured salt. (C) Vermilon (HgS) is a red coloured compound. (D) All of these. Comprehension # 4 Read the following graph and gives the answer for the following questions. Re Series 3 H/KJ mol -1 Tc Series 2 Series 1 Mn Atomic number Trends in enthalpies of atomisation of transition elements 1. The dip in the boiling point of manganese in 3d series is due to : (A) less delocalisation of valence electrons owing to extra stable half filled configuration. (B) smaller size of atom. (C) less electronegativity of atom. (D) all of these 2. Consider the following statements : (I) The transition elements (except the 12th group elements) are very much hard and have low volatility. (II) Generally in a given series the melting points of the transition elements rises to a maximum and then fall as the atomic number increases. (III) Transition metals have high thermal and electrical conductivity and metallic luster. Select the correct from the codes given. (A) I and III only (B) II and III only (C) All of these (D) None of these Comprehension # 5 Pyrolusite ore on oxidation with KClO 3/KNO3 in basic medium produces dark green coloured compound (A), which on electrolysis produces a purple coloured compound (B). The purple coloured compound can be crystallised to deep purple rhombic prisms. It shows different reactions in different mediums. Excess of compound (B) on heating with concentrated H 2SO4 gives an explosive oil (C), which on heating decomposes to gives another compound (D) along with oxygen. 1. 2. The nature of compound (C) is : (A) basic (B) acidic (C) neutral (D) amphoteric On passing CO2 in the solution of (A), a purple coloured solution along with brown precipitate is observed. Select the correct statement. (A) This is a disproportionation reaction where oxidation number changes from +6 to +7 , +4. (B) This is a comproportionation reaction where oxidation number changes from +3 to +2. (C) both (A) and (B) (D) none TRANSITION ELEMENTS 3. Identify (D) . (A) Mn2O7 (B) MnO2 (C) MnSO4 (D) Mn2O3 4. When (D) reacts with PbO 2/HNO3 it produces a purple/pink coloured compound (E). Identify (E). (A) NaMnO4 (B) Mn(OH)2 (C) HMnO4 (D) Na2MnO4 5. Red coloured oxide (M) whose cation has pseudo inert electronic configuration reacts with compound (B) in acidic medium gives another oxide (N) which is black in colour. When sulphate of its metal is reacted with K4[Fe(CN) 6] it produces brown precipitate. Select the correct statement. (A) The brown precipitate formed is Cu2[Fe(CN) 6] (B) The red coloured oxide is Cu2O (C) The black coloured oxide is CuO (D) All of these Comprehension # 6 Photography is based on the nature of silver halides. Except AgF, the silver halides are photosensitive. These undergo decomposition in light and turn black due to formation of free silver. Light 2AgBr   2Ag + Br2 The photographic plates or films are prepared in a dark and dust free room by applying a light sensitive mixture called emulsion which is prepared by adding 20 per cent aqueous solution of silver nitrate to ammonium bromide solution containing gelatin. When such a film is exposed, the emulsion gets affected. Since different parts of the body reflect light of varied intensity, the film or plate is affected proportionately. An actual but inverted image of the object is thus formed on the film or plate which is not visible to the eye. It is, therefore, called the latent image. When this exposed film or plate is dipped in a developer which contains a reducing agent, the parts affected most during exposure are reduced to maximum. The image becomes visible. It is called a negative. The remaining sensitive emulsion on the negative is removed by dissolving it in hypo solution (fixer). Finally, a positive of the negative already prepared is made on silver bromide paper. 1. The compound formed on the unexposed photographic film or plate is : (A) silver nitrate. (B) ammonium bromide. (C) diamminesilver bromide. (D) silver bromide. 2. The exposed part of the film or plate after developing contains : (A) silver metal (B) silver oxide (C) silver bromide(D) silver nitrate. 3. The solution of the developer consists : (A) alkaline solution of pyrogallol (C) either (A) or (B) (B) alkaline solution of quinol (D) neither (A) nor (B). 4. Silver halides are used in photography because these compounds : (A) are insoluble in water (B) are affected by light (C) are soluble in ammonia solution (D) easily stick on the surface of photographic plate or film 5. Silver bromide dissolves in hypo solution forming : (A) Ag2S2O3 (B) Ag2S (C) Na3[Ag(S2O3)2] (D) NaAgS2O3 TRANSITION ELEMENTS EXERCISE - 3 : PART # I 1. A q, s; B r, s ; C p, s ; D p, s 2. A r, B s ; C p ; D q 3. A s ; B q, r ; C q, D p 4. A r, s ; B r, s ; C p, q ; D p 5. A r ; B s ; C p ; D q 6. A t ; B s ; C p ; D q ; E r 7. A q, r, s ; B p, q, r ; C p, q, s ; D q, r 8. A q, s ; B q ; C  p ; D r. 9. A r, s ; B p, q ; C p, r, s ; D r, s. PART # II Comprehension # 1 : 1. D 2. A 3. B Comprehension # 2 : 1. B 2. C 3. C Comprehension # 3 : 1. C 2. C 3. D Comprehension # 4 : 1. A 2. C Comprehension # 5 : 1. B 2. A 3. Comprehension # 6 : 1. D 2. A 3. 4. D B 4. C 5. D C 4. B 5. C