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Questions Related to chemistry

Among the following complexes (K-P) :
$K _3[Fe(CN _6]-K  $ and $  [Co(NH _3) _6]Cl _3-L$ ; 
$Na _3[Co(oxalate) _3]-M $ and    $  [Ni(H _2O) _6]Cl _2-N$ ;
$K _2[Pt(CN) _4]-O$ and $[Zn(H _2O) _6](NO _3) _2 - P$;
the diamagnetic complexes are:

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. K,L,M,N

  2. K,M,O,P

  3. L,M,O,P

  4. all 

Show answer
Correct Option: C
Explanation:

$K _3[Fe(CN _6]-K  $ = $ 3d^5$ it is paramagnetic 


 $  [Co(NH _3) _6]Cl _3-L$ = $3d^6$ is diamagnetic

$Na _3[Co(oxalate) _3]-M $ = $3d^6$ is diamagnetic 

 $  [Ni(H _2O) _6]Cl _2-N$ = $3d^8$ is paramagnetic

$K _2[Pt(CN) _4]-O$ = $d^3 $ it is diamagnetic

 and $[Zn(H _2O) _6](NO _3) _2 - P$;= $ d^6$ it is diamagnetic

According to Werner's coordination theory, there are _______ kinds of valency, _______ and ___. The primary valency of a central metal ion is satisfied with _____.

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. three, negative, positive, cations

  2. different, negative, positive, anions

  3. two, primary, secondary, anions

  4. two, saturated, unsaturated, cations

Show answer
Correct Option: C
Explanation:

According to Werner's coordination theory, there are two kinds of valency, primary and secondary. The primary valency of a central metal ion is satisfied with anions.
For example, in $[Cu(NH _3) _4]SO _4$ primary valency is 2 and secondary valency is 4.
Secondary valence refers to coordination number. Since copper is coordinated to 4 ammonia ligands, secondary valence is 4. Primary valence is satisfied by anions. Since sulphate ion has $-2$ charge, primary valence is 2.

Which of the following sets of examples and geometry of the compounds is not correct?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. Octahedral - $[Co(NH _3) _6]^{3+}, [Fe(CN) _6]^{3-}$

  2. Square planar - $[Ni(CN) _4]^{2-}, [Cu(NH _3) _4]^{2+}$

  3. Tetrahedral- $[Ni(CO) _4], [ZnCl _4]^{2-}$

  4. Trigonal bipyramidal - $[Fe(NH _3) _6]^{2+}, [CuCl _4]^{2-}$

Show answer
Correct Option: D
Explanation:

$[Fe(NH _3) _6]^{2+}=Fe^{2+}=[Ar]3d^6=$ Octahedral.

Hybridisation is $=sp^3d^2$ .

$[CuCl _4]^{2+}=Cu^{2+}=[Cu]3d^{9}=$ Tetrahedral.
Hybridisation $=$ $sp^3$

These two do not have trigonal bipyramidal geometry.

Which of the following complexes will have a tetrahedral shape?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $[PdCl _4]^{2-}$

  2. $[Pd(CN) _4]^{2-}$

  3. $[Ni(CN) _4]^{2-}$

  4. $[NiCl _4]^{2-}$

Show answer
Correct Option: D
Explanation:

$[NiCl _4]^{2-}=$ $Cl^-\rightarrow $ Weak field ligand.

$\Rightarrow Ni^{2+}\Rightarrow [Ar]3d^8$
As the ligands is weak field ligands the complex has tetrahedral geometry of $sp^3$ hybridisation.

The two isomers X and Y with the formula $Cr(H _2O) _5ClBr _2$ were taken for experiment on depression in freezing point. It was found that one mole of X gave depression corresponding to $2$ moles of particles and one mole of Y gave depression due to $3$ moles of particles. The structural formulae of X and Y respectively are:

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $[Cr(H _2O) _5Cl]Br _2$; $[Cr(H _2O) _4Br _2]Cl\cdot H _2O$

  2. $[Cr(H _2O) _5Cl)]Br _2$; $[Cr(H _2O) _3ClBr]\cdot 2H _2O$

  3. $[Cr(H _2O) _5Br]BrCl$; $[Cr(H _2O) _4ClBr]Br\cdot H _2O$

  4. $[Cr(H _2O) _4Br _2]Cl\cdot H _2O$; $[Cr(H _2O) _5Cl]Br _2$

Show answer
Correct Option: D
Explanation:

$Cr(H _2O) _5ClBr _2\longrightarrow$ 2 moles of particle.

It compoubnd is $[Cr(H _2O) _4(Br _2)]Cl.H _2O$
It gives $[Cr(H _2O) _4Br _2]^{+},C\bar l\Rightarrow $ Two particles.
So, $X=[Cr(H _2O) _4Br _2]Cl.H _2O$
If $Y=[Cr(H _2O) _5Cl]Br _2$
It gives $[Cr(H _2O) _5Cl^{2+},2B\bar r\Rightarrow $ 3 particles.

Number of chlorides satisfying secondary valency in $CoCl _{3},\ 4NH _{3}$

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $1$

  2. $2$

  3. $3$

  4. $6$

Show answer
Correct Option: B

The secondary valency of Chromium in $[Cr(en) _3]CI _3$ is

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. 6

  2. 3

  3. 2

  4. 4

Show answer
Correct Option: A

According to Werner’s theory of valency transition metals possesses:

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. only one type of valency

  2. two types of valencies

  3. three types of valencies

  4. four types of valencies

Show answer
Correct Option: B
Explanation:

According to Werner’s theory of valence, transition metals has two valencies are primary valencies and secondary valency.
Primary valencies are those which are statisfied by ligands through coordination bonds and charge that remained on the coordination sphere is satisfied by secondary valence.


Hence, the correct option is $B$

Which of the following alkaline earth metal sulphates has hydration enthalpy higher than the lattice enthalpy ?

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. $SrSO _2$

  2. $MgSO _2$

  3. $CaSO _4$

  4. None

Show answer
Correct Option: B

The co-ordination number of a metal in co-ordination compound is:

chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

  1. same as primary valency

  2. sum of primary and secondary valences

  3. same as secondary valency

  4. none of the above

Show answer
Correct Option: C
Explanation:

The secondary valency is equal to the coordination number the secondary valency are non ionizable valencies. These are satisfied by neutral molecules or negative ions.  For example in $[Ni(CO) _4]$ the coordination number of Ni metal is four and its secondary valency is also four.