d- and f-Block Elements

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Given below are two statements :Statement I : Ferromagnetism is considered as an extreme form of paramagnetism.Statement II : The number of unpaired electrons in a Cr^2+ ion (Z = 24) is the same as that of a Nd^3+ ion (Z = 60).In the light of the abo… Answer: 3. Statement I is true but Statement II is false Statement I is true: ferromagnetism is the extreme form of paramagnetism (domains a... Colour, catalytic and magnetic properties, complexes, interstitial compounds, alloys 1 answer
Match List - I with List - IIList-I: A. Haber process B. Wacker oxidation C. Wilkinson catalyst D. Ziegler catalystList-II: I. Fe catalyst II. PdCl_2 III. [(PPh_3)_3RhCl] IV. TiCl_4 with Al(CH_3)_3Choose the correct answer from the options given belo… Answer: 3. A-I, B-II, C-III, D-IV Haber process: Fe catalyst (I). Wacker oxidation (ethene to ethanal): PdCl₂ (II). Wilkinson catalyst: [(PP... Colour, catalytic and magnetic properties, complexes, interstitial compounds, alloys 1 answer
The pair of lanthanoid ions which are diamagnetic is Answer: 2. Ce⁴⁺ and Yb²⁺ Key idea: diamagnetic means no unpaired electrons, so 4f⁰ or 4f¹⁴ . mathrmCe⁴⁺ : 4f⁰ ; mathrmYb²⁺ : 4f¹⁴ . Both dia... Lanthanoids and lanthanoid contraction 1 answer
'Spin only' magnetic moment is same for which of the following ions?A. Ti^3+ B. Cr^2+ C. Mn^2+ D. Fe^2+ E. Sc^3+Choose the most appropriate answer from the options given below: Answer: 2. B and D only Key idea: μ=√(n(n+2)) BM, so equal unpaired electrons give equal moment. mathrmTi³⁺ ( d¹ ): 1 mathrmCr²⁺ ( d⁴ ): 4 m... Colour, catalytic and magnetic properties, complexes, interstitial compounds, alloys 1 answer
The E^° value for the Mn^3+/Mn^2+ couple is more positive than that of Cr^3+/Cr^2+ or Fe^3+/Fe^2+ due to change of Answer: 4. d⁴ to d⁵ configuration Key idea: a high E^° for M³⁺/M²⁺ means M³⁺ is easily reduced to a very stable M²⁺ . mathrmMn³⁺ is d⁴ ; on... Trends: ionization enthalpy, oxidation states, atomic radii 1 answer
The reaction that does NOT take place in a blast furnace between 900 K to 1500 K temperature range during extraction of iron is : Answer: 2. Fe ₂ O ₃ + CO → 2FeO + CO ₂ Key idea: The blast furnace has temperature zones: the reduction of Fe₂O₃ to FeO by CO takes place in... Transition elements: configuration, occurrence and characteristics 1 answer
Which of the following statements are INCORRECT?A. All the transition metals except scandium form MO oxides which are ionic.B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc_2O_3 to Mn_2O_7… Answer: 4. C and D only Key idea: Recall the d-block oxide trends. A. Correct: MO oxides (except Sc) are ionic. B. Correct: the group oxidat... Trends: ionization enthalpy, oxidation states, atomic radii 1 answer
The stability of Cu^2+ is more than Cu^+ salts in aqueous solution due to - Answer: 4. hydration energy. Key idea: Stability in aqueous solution depends on the overall enthalpy change, where hydration enthalpy often... Trends: ionization enthalpy, oxidation states, atomic radii 1 answer
In the neutral or faintly alkaline medium, KMnO_4 oxidises iodide into iodate. The change in oxidation state of manganese in this reaction is from Answer: 2. +7 to +4 Key idea: in neutral or weakly alkaline medium permanganate is reduced to MnO₂ . 2MnO₄^-+H₂O+I^-→2MnO₂+2OH^-+IO₃^- . Mn... K2Cr2O7 and KMnO4 1 answer
Gadolinium has a low value of third ionisation enthalpy because of Answer: 3. high exchange enthalpy Key idea: exchange enthalpy stabilises half-filled subshells. Gd is [Xe]4f⁷5d¹6s² . Removing the third ele... Lanthanoids and lanthanoid contraction 1 answer
Match List - I with List - II.List - I (Ores): (a) Haematite (b) Magnetite (c) Calamine (d) KaoliniteList - II (Composition): (i) Fe_3O_4 (ii) ZnCO_3 (iii) Fe_2O_3 (iv) [Al_2(OH)_4Si_2O_5]Choose the correct answer from the options given below : Answer: 3. (a) - (iii), (b) - (i), (c) - (ii), (d) - (iv) Key idea: recall ore compositions. Haematite: Fe₂O₃ (iii) Magnetite: Fe₃O₄ (i) Cal... Transition elements: configuration, occurrence and characteristics 1 answer
The incorrect statement among the following is : Answer: 2. Most of the trivalent Lanthanoid ions are colorless in the solid state. Key idea: compare f-block properties. Actinoid contractio... Lanthanoids and lanthanoid contraction 1 answer
Zr (Z=40) and Hf (Z=72) have similar atomic and ionic radii because of : Answer: 3. lanthanoid contraction Key idea: lanthanoid contraction. Between Zr (4d) and Hf (5d) come the 14 lanthanoids, whose poor shieldin... Lanthanoids and lanthanoid contraction 1 answer
The maximum temperature that can be achieved in blast furnace is : Answer: 2. upto 2200 K Key idea: this is a recall fact for iron extraction. In the blast furnace the temperature rises from about 500 K at t... Transition elements: configuration, occurrence and characteristics 1 answer
Which one of the following methods can be used to obtain highly pure metal which is liquid at room temperature ? Answer: 3. Distillation Key idea: the metal liquid at room temperature is mercury, which is volatile with a low boiling point (630 K). Disti... Transition elements: configuration, occurrence and characteristics 1 answer
The calculated spin only magnetic moment of Cr^2+ ion is : Answer: 2. 4.90 BM Spin-only moment: μ=√(n(n+2)) BM, where n is the number of unpaired electrons. Cr (Z=24): 3d⁵4s¹ . mathrmCr²⁺ : 3d⁴ , so... Colour, catalytic and magnetic properties, complexes, interstitial compounds, alloys 1 answer
Identify the correct statement from the following : Answer: 4. Pig iron can be moulded into a variety of shapes. Check each statement. (1) Wrought iron is the purest form of iron (about 0.2% c... Transition elements: configuration, occurrence and characteristics 1 answer
Identify the incorrect statement. Answer: 4. The oxidation states of chromium in CrO ₄²⁻ and Cr ₂ O ₇²⁻ are not the same. Check each statement. (1) mathrmCr³⁺ (half-filled t_... Trends: ionization enthalpy, oxidation states, atomic radii 1 answer
The manganate and permanganate ions are tetrahedral, due to : Answer: 1. The π -bonding involves overlap of p-orbitals of oxygen with d-orbitals of manganese In MnO₄^- and mathrmMnO₄²⁻ , Mn uses sp³ hyb... K2Cr2O7 and KMnO4 1 answer
Which one is malachite from the following ? Answer: 4. CuCO ₃ .Cu(OH) ₂ Malachite is the green basic copper carbonate CuCO₃· Cu(OH)₂ . CuFeS₂ is copper pyrites and Fe₃O₄ is magnetite.... Transition elements: configuration, occurrence and characteristics 1 answer
The reason for greater range of oxidation states in actinoids is attributed to : Answer: 2. 5f, 6d and 7s levels having comparable energies Key idea: a wide range of oxidation states needs electrons from orbitals of simil... Actinoids 1 answer
Extraction of gold and silver involves leaching with CN^- ion. Silver is later recovered by : Answer: 3. displacement with Zn Key idea: Ag is recovered from the cyanide complex by a more electropositive metal. 2[Ag(CN)₂]^- + Zn → [Zn(... Transition elements: configuration, occurrence and characteristics 1 answer
Which one of the following statements related to lanthanons is incorrect? Answer: 2. All the lanthanons are much more reactive than aluminium. Key idea: check each statement against NCERT facts on lanthanoids. Stat... Lanthanoids and lanthanoid contraction 1 answer
Which one of the following statements is correct when SO_2 is passed through acidified K_2Cr_2O_7 solution ? Answer: 4. Green Cr₂(SO₄)₃ is formed. Key idea: SO₂ is a reducing agent and acidified dichromate is an oxidising agent. mathrmCr₂O₇²⁻+3SO₂+2... K2Cr2O7 and KMnO4 1 answer

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