Tag: d and f block elements

Questions Related to d and f block elements

Which of the following compounds is not coloured ?

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

  1. $ Na _{2}[CuCl _{4}] $

  2. $ Na _{2}[CdCl _{2}] $

  3. $ [Cr(H _{2}O) _{6}]Cl _{3} $

  4. all of the above

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Correct Option: B
Explanation:

The outer shell electronic configuration of $Cu^{2+}$ has $3d^{9}$ configuration and contain 1  unpaired electron, thus it is coloured.

$Na _2[CdCl _2]$, compound is not coloured because of central atom $Cd$ which has $4d^{10} 5s^2$ electronic configuration so transition do not occur.
Hence option B 

The color of $KMn{ O } _{ 4 }$ is due to:

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

  1. L-> M charge transfer transition

  2. $\sigma -{ \sigma }^{ * }$ transition

  3. M-> L charge transfer transition

  4. d-d transition

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Correct Option: A
Explanation:

The color in $KMnO _4$ arises from an electronic transition.

In the permanganate ion $MnO _4^{-}$, manganese is in the +7 oxidation state, so it has no d electrons. Photons promote an electron from the highest energy molecular orbital to an empty d orbital on the manganese. When a photon of light is absorbed, this charge transfer takes place from L to M.

Choose the correct statement.

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

  1. Only few transition metal complexes are coloured

  2. d-orbital are degenerated hence, they form complexes

  3. Transition metal complexes reflect the complimentary colour of absorbed colour

  4. Energy difference between ${ t } _{ 2(g) }$ and ${ t } _{ g }$ level is very large

Show answer
Correct Option: C
Explanation:

During this d-d transition process, the electrons absorb certain energy from the radiation and emit the remainder of energy as colored light. The color of ion is complementary of the color absorbed by it. hence, colored ion is formed due to d-d transition which falls in the visible region for all transition elements.

Which of the following  is expected to form colourless complex?

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

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

  2. ${ Cu }^{ + }$

  3. ${ Ti }^{ 3+ }$

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

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Correct Option: B
Explanation:
$Cu^+$ is colourless 
D block elements of periodic table are called as Transition elements. Transition elements have partially filled d orbitals. The colour for the elements of D block is due to transition of electrons which is called as  d -Transition for which presence of partially filled d electrons is must.
copper  Cu , has 29 electrons. 
so  electronic configuration will be $1s^22s^22p^63s^23p^64s^13d^{10}$
but in case of $Cu^+$ ion, 28 electrons so:
electronic configuration will be $1s^22s^22p^63s^23p^63d^{10}$
$Cu^+$ ion will loose its $4s^1$ electron,  and as it has filled $3d^{10}$ orbital,therefore no transition  and hence $Cu^+$ ion will not have any colour.


Out of $TiF _{6}^{2-},\ CoF _{6}^{3-},\ Cu _{2}Cl _{2}$ and $NiCl _{4}^{2-}$, the colourless sphere are..... 

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

  1. $Cu _{2}Cl _{2},\ NiCl _{4}^{2-}$

  2. $TiF _{6}^{2-},\ Cu _{2}Cl _{2}$

  3. $CoF _{6}^{3-},\ NiCl _{4}^{2-}$

  4. $TiF _{6}^{2-},\ CiF _{6}^{3-}$

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Correct Option: B

Which of the following compound is expected to be coloured?

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

  1. $\,{\text{AgN}}{{\text{O}} _3}$

  2. $\,{\text{CuS}}{{\text{O}} _4}$

  3. ${\text{CuCl}}$

  4. ${\text{ZnC}}{{\text{l}} _{\text{2}}}$

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Correct Option: A

When $ZnO$ is heated, it appears of _______colour due to metal excess defect.

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

  1. pink

  2. yellow

  3. violet

  4. blue

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Correct Option: A

The color of $KMnO _{4}$  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. $L\rightarrow M$ charge transfer transition

  3. $\sigma-\sigma^{*}$ transition

  4. $M\rightarrow L$ charge transfer transition

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Correct Option: A

Pair of ions which give blue colour in aqueous state: $V^{+4},\ Ni^{+2},\ Ti^{+3},\ Co^{+2},\ Fe^{+3}\ and\ Cu^{+2}$.

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

  1. $V^{+4}, Cu^{+2}$

  2. $Co^{+2}, Ni^{+2}$

  3. $Fe^{+3}, Ti^{+3}$

  4. $Co^{+2}, Fe^{+3}$

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Correct Option: A

Which of the following compounds are coloured due to charge transfer spectra?

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

  1. ${K} _{2}{Cr} _{2}{O} _{7}$

  2. $KMn{O} _{4}$

  3. $Cu{SO} _{4}.5{H} _{2}O$

  4. Both (1) and (2)

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Correct Option: D