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

Which of the following ion will not form coloured aqueous solution?

  1. $Ni^{2+}$
  2. $Fe^{3+}$
  3. $Ti^{4+}$
  4. $Cu^{2+}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
$ \displaystyle Ni^{2+}$ ion with $ \displaystyle 3d^8$ outer electronic configuration has two unpaired electrons. It will form a green coloured aqueous solution.

$ \displaystyle Fe^{3+}$ ion with $ \displaystyle 3d^5$ outer electronic configuration has five unpaired electrons. It will form yellow coloured aqueous solution.

$ \displaystyle Ti^{4+}$ ion will not form coloured aqueous solutionaas it does not contain unpaired electrons.
$ \displaystyle Ti^{4+}$ ion with $ \displaystyle 3d^0$ outer electronic configuration has zero unpaired electrons.


$ \displaystyle Cu^{2+}$ ion with $ \displaystyle 3d^9$ outer electronic configuration has one unpaired electron. It will form blue coloured aqueous solution.

Hence, option $C$ is correct.

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 orbitals are degenerate for $[Cr(H _2O) _6]^{3+}$?

  1. $d _{x^2-y^2},d _{xy}$
  2. $d _{xy},d _{yz}$
  3. $d _{x^2-y^2},d _{yz}$
  4. $d _{z^2},dxy$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Solution:- (B) ${d} _{xy}, {d} _{yz}$

$[Cr(H _2O) _6]^{3+} $ has $d^2sp^3$ hybridization .$dxy,dyz,dzx$,orbitals are degenerate.

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

Ammonium dichromate is used in fire works. The green colored powder blow in the air is:

  1. $Cr{O} _{3}$
  2. ${Cr} _{2}{O} _{3}$
  3. $Cr$
  4. $CrO ({O} _{2})$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$(\mathrm{NH} _4) _2\mathrm{Cr} _2\mathrm{O} _7\xrightarrow{\Delta} \mathrm{Cr} _2\mathrm{O} _3+\mathrm{N} _2+4\mathrm{H} _2\mathrm{O}$

The green-coloured $ Cr _2O _3$ powder is blown in the air by the large volume of $ N _2$ and water vapour produced and settles like dust from the volcano. 

Hence, the correct option is $\text{B}$
Multiple choice chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

Which one of the following forms a colorless solution in aqueous medium?

  1. ${Cr}^{3+}$
  2. ${Ti}^{3+}$
  3. ${Sc}^{3+}$
  4. ${V}^{3+}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Cr^{3+}$ = $3d^3$ = coloured

$Ti^{3+}$ =  $3d^1$ = coloured

$V^{3+}$ =  $3d^2$ = coloured

$Sc^{3+}$ has electron configuration of [Ar] $4s^0  3d^0$. Therefore without any unpaired electrons it forms a colorless solution in aqueous medium.