Tag: d and f block elements

Questions Related to d and f block elements

Which of the following is not correct?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${\text{TiC}}{{\text{l}} _{\text{4}}}$ is a colourless compound.

  2. $\left[ {{\text{Cr}}{{\left( {{\text{N}}{{\text{H}} _{\text{3}}}} \right)} _{\text{6}}}} \right]{\text{C}}{{\text{L}} _{\text{3}}}$ is a coloured compound

  3. ${{\text{K}} _{\text{3}}}\left[ {{\text{V}}{{\text{F}} _{\text{6}}}} \right]$ is a colourless compound

  4. $\;\left[ {{\text{Cu}}{{\left( {{\text{NCC}}{{\text{H}} _{\text{3}}}} \right)} _{\text{4}}}} \right]\left[ {{\text{B}}{{\text{F}} _{\text{4}}}} \right]$ is a colourless compound

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Correct Option: A

The colour imparted by $Co(II)$ compounds to glass is 

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. green

  2. deep blue

  3. yellow

  4. red

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Correct Option: B
Explanation:
 Vanadium yellow-green 
 Chrome emerald green 
 Iron Coke bottle green 
 Manganese amethyst 
 Cobalt violet blue 
 Copper greenish blue to blue 
 Nickel grayish brown 
 Selenium salmon pink 
 Cerium- Titanium yellow 
 Neodymium dichroic violet-pink 
 Uranium yellow (fluorescent 

Which of the ions will give colorless aqueous solution?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${Ni}^{2+}$

  2. ${Fe}^{2+}$

  3. ${Cu}^{2+}$

  4. ${Cu}^{+}$

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Correct Option: D
Explanation:

${Ni}^{2+}$ is light green, ${Fe}^{2+}$ is pale green, 


${Cu}^{2+}$ is blue and ${Cu}^{1+}$ is colorless in aqueous solution as its outermost configuration is $3d^{10}$ so thei is no unpaired electron which causes colour.

Hence ,option D is correct.

The color of the transition metal ions is due to:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $d-d$ transition

  2. charge transfer

  3. change in the geometry

  4. none

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Correct Option: A,B
Explanation:

In case of transition elements, where the d-level is not completely filled, it is possible to promote an electron from a lower energy d-orbital to a higher energy d-orbital by absorption of a photon of electromagnetic radiation having an appropriate energy. Electromagnetic radiations in the visible region of the spectrum often possess the appropriate energy for such transitions. 

Which of the following statements are correct with reference to the ferrous and ferric ions?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${Fe}^{3+}$ gives brown color with potassium ferricyanide

  2. ${Fe}^{2+}$ gives blue precipitate with potassium ferricyanide

  3. ${Fe}^{3+}$ gives red color with potassium thiocyanate

  4. ${Fe}^{2+}$ gives brown color with ammonium thiocyanate

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Correct Option: B,C

Which one of the following ionic species will not impart color to an aqueous solution?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. ${Ti}^{4+}$

  2. ${Cu}^{+}$

  3. ${Zn}^{2+}$

  4. ${Cr}^{3+}$

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Correct Option: A,B,C
Explanation:
The transition metal ions which have completely filled d-orbitals are colorless.

The transition metal ions which have completely empty d-orbitals are also colorless.

$ Cr^{3+}$ has a blue-green color.  because contain unpair electrons.

Rest all are colorless. 

The colorless species is:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $V{Cl} _{3}$

  2. $VO{SO} _{4}$

  3. ${Na} _{3}{VO} _{4}$

  4. $\left[ V{ \left( { H } _{ 2 }O \right) } _{ 6 }{ SO } _{ 4 } \right] .{ H } _{ 2 }O$

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Correct Option: C
Explanation:

$ VCl _3$ is green.

 
$ VOSO _4$ is blue. 

$ Na _3VO _4$ is colorless vanadium is present in +5 oxidation state .it does not have any unpaired electron.
 
$\left[ V{ \left( { H } _{ 2 }O \right)  } _{ 6 }{ SO } _{ 4 } \right]$ .${ H } _{ 2 }O$ is purple.

The aqueous solution of the salt will colored in the case of:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $Zn{({NO} _{3})} _{2}$

  2. $Li{NO} _{3}$

  3. $Co{({NO} _{3})} _{2}$

  4. $Cr{Cl} _{3}$

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Correct Option: C,D
Explanation:

$ Co^{2+}$ = $3d^7$  


$Cr^{3+}$ = $3d^3$
 
$ Co^{2+}$ and $Cr^{3+}$   will have unpaired electrons and hence are expected to have aqueous solution of the salt colored.

What is/are true statement?

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. Ions of $d$-block elements are colored due to $d-d$ transition

  2. Ions of $f$-block elements are colored due to $f-f$ transtition

  3. ${ \left[ Sc{ \left( { H } _{ 2 }O \right) } _{ 6 } \right] }^{ 3+ },{ \left[ Ti{ \left( { H } _{ 2 }O \right) } _{ 6 } \right] }^{ 4+ }$ are colored complexes.

  4. ${Cu}^{+}$ is colorless ion.

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Correct Option: A,B,D
Explanation:
$Cu^+$ is colourless because it doesn't contain any electrons which can absorb light. .

In ${ \left[ Sc{ \left( { H } _{ 2 }O \right)  } _{ 6 } \right]  }^{ 3+ }$, $ Sc^{3+}$  is $ d^0$ system and hence colorless.

Hence,option C is incorrect.

The aqueous solutions of the following salts will be colored in the case of:

chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

  1. $Zn{({NO} _{3})} _{2}$

  2. $Li{NO} _{3}$

  3. $Co{({NO} _{3})} _{2}$

  4. $Cr{Cl} _{3}$

  5. Potash alum

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Correct Option: C,D
Explanation:
${Co}^{2+}$
$\uparrow \downarrow $ $\uparrow \downarrow $ $\uparrow $ $\uparrow $ $\uparrow $
$z=27$
$Co=[Ar]{3d}^{7}{4s}^{2}$
${Co}^{2+}=[Ar]{3d}^{7}$
Two unpaired electrons present.

${Cr}^{3+}$:
$z=24$
$Cr=[Ar]{3d}^{5}{4s}^{1}$
${Cr}^{3+}=[Ar]{3d}^{3}$
$\uparrow $ $\uparrow $ $\uparrow $
$Co{({NO} _{3})} _{2}$ and $Cr{Cl} _{2}$ have unpaired electron; hence, they are colored.

The compounds have $ Zn^{2+}, Li^+, Co^{2+} and Cr^{3+}$ with 0, 0, 2 and 3 unpaired electrons. Hence option C and D are correct. Potash alum is colorless.