NCERT solutions for Class 12 Chemistry chapter 8 - The d-block and f-block Elements [Latest edition]

Silver atom has completely filled d orbitals (4d¹⁰) in its ground state. How can you say that it is a transition element?

Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why?

The E^θ(M²⁺/M) value for copper is positive (+0.34V). What is possibly the reason for this? (Hint: consider its high Δ_aH^θ and low Δ_hydH^θ)

How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?

Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

Which is a stronger reducing agent Cr²⁺ or Fe²⁺ and why?

Calculate the ‘spin only’ magnetic moment of M²⁺_(aq) ion (Z = 27).

Explain why Cu⁺ ion is not stable in aqueous solutions?

How would you account for the following : Actinoid contraction is greater than lanthanoid contraction.

Write down the electronic configuration of Cr³⁺

Write down the electronic configuration of Pm³⁺

Write down the electronic configuration of Cu⁺

Write down the electronic configuration of Ce⁴⁺

Write down the electronic configuration of Co²+

Write down the electronic configuration of Lu²⁺

Write down the electronic configuration of Mn²⁺

Write down the electronic configuration of Th⁴⁺

Why are Mn²⁺compounds more stable than Fe²⁺ towards oxidation to their +3 state?

Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.

What may be the stable oxidation state of the transition element with the following d electron configurations in the ground state of their atoms : 3d³,3d⁵, 3d⁸and 3d⁴?

Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.

Define lanthanoid contraction.

What are the characteristics of the transition elements and why are they called transition elements? 

Which of the d-block elements may not be regarded as the transition elements?

In what way is the electronic configuration of the transition elements different from that of the non-transition elements?

What are the different oxidation states exhibited by the lanthanoids?

Explain giving reasons:

Transition metals and many of their compounds show paramagnetic behaviour.

Why do the transition elements have higher enthalpies of atomisation?

How would you account for the following : Transition metals form coloured compounds

Explain giving reasons:  Transition metals and their many compounds act as good catalyst.

What are interstitial compounds ?

How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.

Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with: (i) iodide (ii) iron(II) solution and (iii) H₂S

Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron(II) ions (ii) SO₂ and (iii) oxalic acid? Write the ionic equations for the reactions.

For M²⁺/M and M³⁺/M²⁺ systems, the `E^theta` values for some metals are as follows:

Cr²⁺/Cr −0.9V

Cr³/Cr²⁺ −0.4 V

Mn²⁺/Mn −1.2V

Mn³⁺ /Mn²⁺ +1.5 V

Fe²⁺ /Fe −0.4V

Fe³⁺/Fe²⁺ +0.8 V

Use this data to comment upon:

(i) The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ or Mn³⁺ and

(ii) The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.

Predict which of the following will be coloured in aqueous solution? Ti³⁺, V³⁺, Cu⁺, Sc³⁺, Mn²⁺, Fe³⁺ and Co²⁺. Give reasons for each.

Compare the stability of +2 oxidation state for the elements of the first transition series.

Compare the chemistry of actinoids with that of the lanthanoids with special reference  to electronic configuration

Compare the chemistry of actinoids with that of the lanthanoids with special reference to: oxidation state

Compare the chemistry of actinoids with that of the lanthanoids with special reference to atomic and ionic sizes

Compare the chemistry of actinoids with that of the lanthanoids with special reference to chemical reactivity.

How would you account for the following:

Of the d⁴species, Cr²⁺ is strongly reducing while manganese(III) is strongly oxidising.

How would you account for the following:

Cobalt(II) is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised.

How would you account for the following: The d¹ configuration is very unstable in ions.

What is meant by ‘disproportionation’? Give two examples of disproportionation reaction in aqueous solution.

Which metal in the first series of transition metals exhibits +1 oxidation state most frequently and why?

Calculate the number of unpaired electrons in the following gaseous ions: Mn³⁺, Cr³⁺, V³⁺ and Ti³⁺. Which one of these is the most stable in aqueous solution?

Give examples and suggest reasons for the following features of the transition metal chemistry:

The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.

Give examples and suggest reasons for the following features of the transition metal chemistry:

A transition metal exhibits highest oxidation state in oxides and fluorides.

Give examples and suggest reasons for the following features of the transition metal chemistry:

 The highest oxidation state is exhibited in oxoanions of a metal.

Indicate the steps in the preparation of K2Cr2O7 from chromite ore.

Indicate the steps in the preparation of:  KMnO4 from pyrolusite ore.

What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.

What are inner transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner transition elements: 29, 59, 74, 95, 102, 104.

The chemistry of the actinoid elements is not so smooth as that of the Lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements

Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element.

Use Hund’s rule to derive the electronic configuration of Ce³⁺ ion and calculate its magnetic moment on the basis of ‘spin-only’ formula.

Name the members of the lanthanoid series which exhibit +4 oxidation state and those which exhibit +2 oxidation state. Try to correlate this type of behavior with the electronic configurations of these elements.

Compare the chemistry of the actinoids with that of lanthanoids with reference to chemical reactivity.

Compare the chemistry of the actinoids with that of lanthanoids with reference to electronic configuration

Compare the chemistry of the actinoids with that of lanthanoids with reference to oxidation states

Write the electronic configurations of the elements with the atomic numbers 61, 91, 101, and 109.

Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points:

(i) electronic configurations,

(ii) oxidation states,

(iii) ionisation enthalpies, and

(iv) atomic sizes.

Write down the number of 3d electrons in each of the following ions:

Ti²⁺, V²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, CO²⁺, Ni²⁺ and Cu²⁺.

Indicate how would you expect the five 3d orbitals to be occupied for these hydrated ions (octahedral).

Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

What can be inferred from the magnetic moment values of the following complex species?

Example Magnetic Moment (BM)

K₄[Mn(CN)₆] 2.2

[Fe(H₂O)₆]²⁺ 5.3

K₂[MnCl₄] 5.9