Tag: general characteristics of first transition series

Questions Related to general characteristics of first transition series

Which of the following ion will not form coloured 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. $Fe^{3+}$

  3. $Ti^{4+}$

  4. $Cu^{2+}$

Show answer
Correct Option: C
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.

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

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

  1. $d _{x^2-y^2},d _{xy}$

  2. $d _{xy},d _{yz}$

  3. $d _{x^2-y^2},d _{yz}$

  4. $d _{z^2},dxy$

Show answer
Correct Option: B
Explanation:

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

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

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

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

  1. $Cr{O} _{3}$

  2. ${Cr} _{2}{O} _{3}$

  3. $Cr$

  4. $CrO ({O} _{2})$

Show answer
Correct Option: B
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 $\text{B}$

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

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

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

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

  3. ${Sc}^{3+}$

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

Show answer
Correct Option: C
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.