Tag: general characteristics of first transition series

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Multiple choice chemistry d and f block elements solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

Which of the following set of metals can form alloy.

  1. $Cu$ and $Au$
  2. $Li$ and $Na$
  3. $Fe$ and $Hg$

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Metals combined with other substances to make them stronger, harder, lighter, or better in some other way. An alloy like this will form only if the atoms of the base metal and those of the alloying agent are of roughly similar size. In most substitution alloys, the constituent elements are quite near one another in the periodic table. 

Corinthian bronze, is an alloy of copper with gold or silver.
Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum.

Multiple choice chemistry d and f block elements solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

Which of the following metals are present in Devarda alloy?

  1. $Cu$
  2. $Al$
  3. $Zn$
  4. $Ag$
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Devarda's alloy is  an alloy of aluminium (44% – 46%), copper (49% – 51%) and zinc (4% – 6%).

Devarda's alloy is used as reducing agent in analytical chemistry for the determination of nitrates after their reduction to ammonia under alkaline conditions.

Hence option A,B and C are correct.

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

Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state? 

  1. $Ag _2SO _4$
  2. $CuF _2$
  3. $ZnF _2$
  4. $Cu _2Cl _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The respective transition elements exists in
$Ag^{+}-{4d}^{10}5s^0$, (have completely filled d orbital)
$Cu^{+2}-3d^{9}4s^0$, (have incompletely filled d orbital)
$Zn^{+2}-3d^{10}4s^0$ , (have completely filled d orbital)
$Cu^{+1}-3d^{10}4s^0$ (have completely filled d orbital),
Since, $Cu^{+2}$ has unpaired electron it will show electron transitions. 
Hence will be coloured.
Multiple choice chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

In which of the following ions, the colour is not due to $d-d$ transition?

  1. $[Ti(H _2O) _6]^{3+}$
  2. $[Cu(NH _3) _4]^{2+}$
  3. $[CoF _6]^{3-}$
  4. $CrO _4^{2-}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Colour is due to d-d transtition ,then such complexes have colour due to d-d transition are surely octahedral complexes.
Among the given options,                                                   
                                         ${ \left[ Ti{ \left( { H } _{ 2 }O \right)  } _{ 6 } \right]  }^{ 3+ }$
                                        ${ \left[ Cu{ \left( { NH } _{ 3 } \right)  } _{ 4 } \right]  }^{ 2+ }$
                                           ${ \left[ { COF } _{ 6 } \right]  }^{ 3- }$
This are octahedral complexes.
$CrO _4^{2-}$ is a salt,it colour is not due to d-d transition.
Multiple choice chemistry d and f block elements coloured complexes magnetic nature of transition metals general characteristics of first transition series

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) $FeSO _4.7H _2O$ (i) Green
(B) $NiCl _2.4H _2O$ (ii) Light Pink
(C) $MNCl _2.4H _2O$ (iii) Pale green
(D) $CoCl _2.6H _20$ (iv) Pink
(E) $Cu _2Cl _2$ (v) Colourless

  1. (A) - (iii), (B) - (iv), (C) - (i), (D) - (ii), (E) - (v)

  2. (A) - (ii), (B) - (iii), (C) - (iv), (D) - (i), (E) - (v)

  3. (A) - (v), (B) - (ii), (C)-(iii), (D) - (iv), (E) - (i)

  4. (A) - (iii), (B)-(i), (C)-(ii), (D) - (iv), (E).- (v)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The colour of the following compounds are:

(i) $FeSO _4$. & $H _2O$ - Pale green.
(II) $NiCl _2$.$4H _2O$ -Green
(iii) $MnCl _2$.$4H _2O$ - Light pink
(iv) $CoCl _2$.$6H _2O$ - Pink
(v) $CuCl _2$ - Colourless.
The colour of the transition metal compounds is due to partially filled d orbitals. Due to that,  d-d transition its complementary colour is seen. 
Hydrated complexes are coloured because in that come H$ _2$O molecules act as a ligand and gets arranged around the central metal atom so as to bring d-d transition.

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

For $Zn^{2+}$, $Ni^{2+}$, $Cu$, and $Cr^{2+}$ which of the following statements is correct?

  1. Only $Zn^{2+}$ is colourless and $Ni^{2+}$, $Cu^{2+}$ and $Cr$ are coloured

  2. All the ions are coloured

  3. All the ions are colourless
  4. $Zn^{2+}$and $Cu^{2+}$ are colourless while $Ni^{2+}$ and $Cr^{2+}$ are coloured
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since $Zn^{+2}$ have fully filled $d$ orbital having no unpaired electrons,it does not undergo electronic transitions,hence colourless.However,rest of the elements given as $Ni^{+2}$ , $Cu^{+2}$ and $Cr^{+2}$ has unpaired electrons which can undergo electronic transitions and hence show colours.