Free NCERT Solutions For Class 12 Chemistry Chapter 8 : The d & f Block Elements Free PDF Download

Question 1:
Write down the electronic configuration of:

Question 2:
Why are Mn2+compounds more stable than Fe2+ towards oxidation to their +3 state?

Question 3: Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

Question 4:
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.

Question 6:
Name the Oxo metal anions of the first series of the transition metals in which the metal exhibits
the oxidation state equal to its group number.

Question 7: What is lanthanoid contraction? What are the consequences of lanthanoid contraction?

Question 8:
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?

Question 9:
In what way is the electronic configuration of the transition elements different from that of the non-transition elements?

Question 11:
Explain giving reasons:
(i) Transition metals and many of their compounds show paramagnetic behaviour.
(ii) The enthalpies of atomisation of the transition metals are high.
(iii) The transition metals generally form coloured compounds.
(iv) Transition metals and their many compounds act as good catalyst.

Question 14:
Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?

Question 16:
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.

Question 20:
Compare the chemistry of actinoids with that of the lanthanoids with special reference to:
(i) electronic configuration (iii) oxidation state
(ii) atomic and ionic sizes and (iv) chemical reactivity

Question 22:
What is meant by ‘disproportionation’? Give two examples of disproportionation reaction in aqueous solution

Solution 22:

Question 25:
Give examples and suggest reasons for the following features of the transition metal chemistry:
(i) The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.
(ii) A transition metal exhibits highest oxidation state in oxides and fluorides.
(iii) The highest oxidation state is exhibited in oxoanions of a metal.

Solution 25:

Question 27:
What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.

Question 33:
Compare the chemistry of the actinoids with that of lanthanoids with reference to:
(i) electronic configuration
(ii) oxidation states and
(iii) chemical reactivity.

Question 35:
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.

Question 37:
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.

Intext Questions

Question 1:
Silver atom has completely filled d orbitals (4d10) in its ground state. How can you say that it is a
transition element?

Question 2:
In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization of zinc is the lowest, i.e. . 1 126KJ mol-1 Why?

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

Question 4:

Question 5:
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?

Question 6:
Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?

Question 8:
Calculate the ‘spin only’ magnetic moment of M2+ (aq) ion (Z = 27)

Question 10:
Actinoid contraction is greater from element to element than lanthanoid contraction. Why?