Recent questions tagged d-and-f-block-elements

From which of the following element pars effect of poor shielding of d and

asked Apr 11, 2018 by akhilam512

1 answer

(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) ?

asked 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.

asked Nov 29, 2016 by meena.p

1 answer

(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

asked Nov 29, 2016 by meena.p

1 answer

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

asked Nov 22, 2016 by meena.p

1 answer

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.

asked Nov 10, 2016 by meena.p

1 answer

(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 $513\;K$.

asked Nov 10, 2016 by meena.p

1 answer

(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

asked Nov 8, 2016 by meena.p

1 answer

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

asked 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 .

asked Nov 1, 2016 by meena.p

1 answer

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

asked Oct 24, 2016 by meena.p

1 answer

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

asked 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

asked Oct 18, 2016 by meena.p

1 answer

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

asked Oct 17, 2016 by meena.p

1 answer

Which of the following is not an example of Disproportionation in acidic medium?

asked Aug 6, 2014 by balaji.thirumalai

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Which of the following is NOT true about Cerium (Atomic Number = 58, Electron configuration = [Xe] 4f$^1$5d$^1$6s$^2$)?

asked Aug 6, 2014 by balaji.thirumalai

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Which of the following is NOT a consequence of Lanthanide contraction?

asked Aug 6, 2014 by balaji.thirumalai

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Which of the following is NOT a point of similarity between Lanthanides and Actinides?

asked Aug 6, 2014 by balaji.thirumalai

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Which of the following is true about the oxidation state of transition metals?

asked Aug 4, 2014 by balaji.thirumalai

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Which of the following has maximum number of unpaired electrons?

asked Aug 4, 2014 by balaji.thirumalai

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Which of the following statements about electron configuration of f-block statements is INCORRECT?

asked Aug 4, 2014 by balaji.thirumalai

1 answer

Why can't the electron configuration of actinides be properly assigned with a high degree of certainty?

asked Aug 4, 2014 by balaji.thirumalai

1 answer

Which of the following pairs have the same electronic configuration?

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Which of the following pairs have the same electronic configuration?

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Which of the following statements regarding the electron configuration in transition metals are TRUE?

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Match the following with their condensed electronic configuration:

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Match the following with their condensed electronic configuration:

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Match the following with their condensed electronic configuration:

asked Aug 2, 2014 by balaji.thirumalai

1 answer

How is the n value of the d sublevel of a f-block element related to the period number of the element?

asked Aug 2, 2014 by balaji.thirumalai

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How is the n value of the d sublevel of a transition element related to the period number of the element?

asked Aug 2, 2014 by balaji.thirumalai

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following equations is not correctly formulated ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer

Which of the following statements is not correct ?

asked Aug 1, 2014 by thanvigandhi_1

1 answer