Recent questions and answers in d- and f-block elements

What is meant by ‘disproportionation’ of an oxidation state? Give an example

answered Jul 19, 2017 by pady_1

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On what ground can you say that scandium (Z = 21) is a transition element but zinc is not.

answered Jul 10, 2017 by pady_1

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<span class="mpa-ignore">Why is Cr2+ reducing and Mn3+ oxidising when both have d 4 configuration?</span></p>

answered Jul 10, 2017 by pady_1

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Why do the transition elements exhibit higher enthalpies of atomisation?

answered Jul 10, 2017 by pady_1

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<span style="font-size:11.0pt;line-height:115%; font-family:"Calibri","sans-serif&quo

answered Jul 10, 2017 by pady_1

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What is Transition element?

asked Jul 6, 2017 by pady_1

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(a) The actinoids exhibit more number of oxidation states and give their common oxidation states. (b)A wellknown orange crystalline compound (A) when burnt impart violet colour to flame. (A) on treating (B) and conc. $H_2SO_4$ gives red gas (C) which gives red yellow solution (D) with alkaline water. (D) on treating with acetic acid and lead acetate gives yellow p. pt. (E). (B) sublimes on heating. Also on heating (B) with NaOH gas (F) is formed which gives white fumes with HCl. What are (A) to (F) ?

answered Dec 29, 2016 by sharmaaparna1

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The chemistry of the actinoid elements is not so smooth as that of the Lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.

answered Nov 29, 2016 by meena.p

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(i) Why are complexes of the d-block elements coloured ? (ii) Why are scandium and Zinc not counted as transition metals even though they belong to the d-block? (iii)When a brown compound of manganers (A) is treated with $Hcl$ it gives a gas (B) . The gas taken in excess , reacts with $Nh_3$ to give an explosive compound A and B

answered Nov 29, 2016 by meena.p

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Assign reasons for the following: (i) The enthalpies of atomisation of transition elements are high. (ii) The transition metals and many of their compounds act as good catalysts. (iii) From element to element the actinoid contraction is greater than the lanthanoid contraction. (iv) The $E^{\circ}$ value for the $Mn ^{3+} / Mn ^{2+}$ couple is much more positive than that of $Cr^{3+} / Cr^{2+}.$ (v) Scandium $(z=21)$ does not exhibit variable oxidation states and yet it is regarded as a transition element

answered Nov 23, 2016 by meena.p

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Account for the following: i)Fluorine does no show variable oxidation states while other members of the halogen family exhibit variable oxidation states. ii)Iodine is more soluble in $KI$ solution than in water. iii)Why do boiling points of noble gases increases down the group? iv)Why ammonia is a good complexing agent? v)Nitric oxide(NO) is a colourless gas becomes brown when released in air.

answered Nov 10, 2016 by meena.p

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(a) Compare non transition and transition elements on the basis of their (i) Variability of oxidation states (ii) stability of oxidation states. (b) Give chemical reactions for the following observations: (i) Potassium permanganate is a good oxidising agent in basic medium. (ii) Inter convertibility of chromate ion and dichromate ion in aqueous solution depends Upon pH of the solution. (iii) Potassium permanganate is thermally unstable at $513\;K$.

answered Nov 10, 2016 by meena.p

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(a)Draw the molecular structure of the following compounds : $(i)N_2O_5 (ii) X_eOF_4$ (b) Why do the d-block elements exhibits a large number of oxidation states than f - block elements

answered Nov 9, 2016 by meena.p

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Why do the d-block elements exhibits a large number of oxidation states than f - block elements

answered Nov 3, 2016 by meena.p

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How would you account for the following ? (i) Many of the transition elements are known to form interstitial compounds . (ii) The metallic radii of the third (5d) series of transition metals are virtually the same as those of the corresponding group members of the second (4d) series .(iii) Lanthanoids form primary +3 ions , while the actinoids usually have higher oxidation state in their compounds , +4 or even +6 typical .

answered Nov 1, 2016 by meena.p

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The second and third rows of transition elements resemble each other much more than they resemble the first row. explain why ?

answered Oct 24, 2016 by meena.p

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Give chemical reactions for the following observations: (i) Potassium permanganate is a good oxidising agent in basic medium. (ii) Inter-convertibility of chromate ion and dichromate ion in aqueous solution depends upon pH of the solution . (iii) Potassium permanganate is thermally unstable at 513 K

answered Oct 24, 2016 by meena.p

1 answer

(A)(a) Compare non transition and transition elements on the basis of their (i) Variability of oxidation states (ii) stability of oxidation states. (b) Give chemical reactions for the following observations: (i) Potassium permanganate is a good oxidising agent in basic medium. (ii) Inter convertibility of chromate ion and dichromate ion in aqueous solution depends Upon pH of the solution. (iii) Potassium permanganate is thermally unstable at $513\;K$. (B) Why do the d - block elements exhibit a large number of oxidation states than f- block elements

answered Oct 18, 2016 by meena.p

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Why do the d - block elements exhibit a large number of oxidation states than f- block elements

answered Oct 17, 2016 by meena.p

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