Tag: general characteristics of first transition series

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

The silver salts like $AgBr$ and $AgI$ are coloured because of:

  1. d-d transition of electrons

  2. charge transfer
  3. polirisation of halid${Ag}^{+}$ by

  4. both (b) and (c)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The silver salts like$AgBr$ and $AgI$ are colored, the color of transition metal ions is due  to the presence of unpaired electron . The electrons which absorbs radiations of color that from the visible or UV spectrum and undergo transition from ground state to excited state within d-sub shells,so it is d-d transitions of electrons.

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

Which of the following compounds is not coloured ?

  1. $ Na _{2}[CuCl _{4}] $
  2. $ Na _{2}[CdCl _{2}] $
  3. $ [Cr(H _{2}O) _{6}]Cl _{3} $

  4. all of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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 

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

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

  1. L-> M charge transfer transition
  2. $\sigma -{ \sigma }^{ * }$ transition

  3. M-> L charge transfer transition

  4. d-d transition
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

Choose the correct statement.

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

Which of the following  is expected to form colourless complex?

  1. ${ Ni }^{ 2+ }$
  2. ${ Cu }^{ + }$
  3. ${ Ti }^{ 3+ }$
  4. ${ Fe }^{ 3+ }$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.


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

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

  1. $Cu _{2}Cl _{2},\ NiCl _{4}^{2-}$
  2. $TiF _{6}^{2-},\ Cu _{2}Cl _{2}$
  3. $CoF _{6}^{3-},\ NiCl _{4}^{2-}$
  4. $TiF _{6}^{2-},\ CiF _{6}^{3-}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

TiF6^2- is colorless (Ti^4+ is d^0, no d-d transitions possible). Cu2Cl2 is also colorless/slightly yellowish as it's copper(I) with full d^10 configuration. The other complexes have partially filled d-orbitals giving color: CoF6^3- (green, Co^3+ d^6) and NiCl4^2- (blue, Ni^2+ d^8). Note: Option D has a typo 'CiF' should be 'CoF'.

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

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

  1. pink

  2. yellow

  3. violet

  4. blue
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Zinc oxide is white at room temperature, but upon heating, it loses oxygen reversibly and forms zinc excess defects. The trapped electrons in interstitial sites occupy specific energy levels, absorbing blue light and reflecting a yellow color. Thus, heated ZnO appears yellow.

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

The color of $KMnO _{4}$  is due to :

  1. $d-d$ transition
  2. $L\rightarrow M$ charge transfer transition
  3. $\sigma-\sigma^{*}$ transition
  4. $M\rightarrow L$ charge transfer transition
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The intensely purple color of the permanganate ion is not due to d-d transitions because manganese is in the +7 oxidation state with a d0 configuration. Instead, it arises from a ligand-to-metal charge transfer (LMCT), where electrons move from the oxygen ligand orbitals to the empty metal orbitals.

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

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

  1. $V^{+4}, Cu^{+2}$
  2. $Co^{+2}, Ni^{+2}$
  3. $Fe^{+3}, Ti^{+3}$
  4. $Co^{+2}, Fe^{+3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

V(4+) (as vanadyl ion) and Cu(2+) (as hydrated copper ion) are well-known for their blue colors in aqueous solutions.