Chemistry · Textbook solutions

The d-and f-Block Elements

Every solved example, exercise, and miscellaneous question, in the order the textbook teaches them. Plus every board question asked from this chapter. · 58 questions

Worked Examples

10 q

Solved Examples

Worked · 10

Eg 4.1 $Z = 21$
Eg 4.2 $Why do the transition elements exhibit higher enthalpies of atomisation?$
Eg 4.3 $Name a transition element which does not exhibit variable oxidation states.$
Eg 4.4 $\text{Cr}^{2+}$
Eg 4.5 $\text{VO}_2^{+} < \text{Cr}_2\text{O}_7^{2-} < \text{MnO}_4^{-}$
Eg 4.6 $E^{\circ}$
Eg 4.7 $E^{\circ}$
Eg 4.8 $Calculate the magnetic moment of a divalent ion in aqueous solution if its atomic number is 25.$
Eg 4.9 $What is meant by 'disproportionation' of an oxidation state? Give an example.$
Eg 4.10 $+4$

$E^{\circ}$	V	Cr	Mn	Fe	Co	Ni	Cu
$(\text{M}^{2+}/\text{M})$	$-1.18$	$-0.91$	$-1.18$	$-0.44$	$-0.28$	$-0.25$	$+0.34$

Intext Questions

10 q

Intext 4.1 $d$
Intext 4.2 $Z = 21$
Intext 4.3 $3d$
Intext 4.4 $E^{\circ}(\text{M}^{2+}/\text{M})$
Intext 4.5 $How would you account for the irregular variation of ionisation enthalpies (first and second) in the first series of the transition elements?$
Intext 4.6 $Why is the highest oxidation state of a metal exhibited in its oxide or fluoride only?$
Intext 4.7 $\text{Cr}^{2+}$
Intext 4.8 $\text{M}^{2+}_{\text{(aq)}}$
Intext 4.9 $\text{Cu}^{+}$
Intext 4.10 $Actinoid contraction is greater from element to element than lanthanoid contraction. Why?$

Exercises

38 q

Ex 4.1 $\text{Cr}^{3+}$
Ex 4.2 $\text{Mn}^{2+}$
Ex 4.3 $+2$
Ex 4.4 $To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.$
Ex 4.5 $d$
Ex 4.6 $Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.$
Ex 4.7 $What is lanthanoid contraction? What are the consequences of lanthanoid contraction?$
Ex 4.8 $d$
Ex 4.9 $In what way is the electronic configuration of the transition elements different from that of the non transition elements?$
Ex 4.10 $What are the different oxidation states exhibited by the lanthanoids?$
Ex 4.11 $Explain giving reasons: (i) Transition metals and many of their compounds show paramagnetic behaviour. (ii) The enthalpies of atomisation of the transition metals are high. (iii) The transition metals generally form coloured compounds. (iv) Transition metals and their many compounds act as good catalyst.$
Ex 4.12 $What are interstitial compounds? Why are such compounds well known for transition metals?$
Ex 4.13 $How is the variability in oxidation states of transition metals different from that of the non transition metals? Illustrate with examples.$
Ex 4.14 $Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?$
Ex 4.15 $\text{H}_2\text{S}$
Ex 4.16 $\text{SO}_2$

Ex 4.17

\text{M}^{2+}/\text{M}

Ex 4.18 $\text{Ti}^{3+}$
Ex 4.19 $+2$
Ex 4.20 $Compare the chemistry of actinoids with that of the lanthanoids with special reference to: (i) electronic configuration (ii) atomic and ionic sizes and (iii) oxidation state (iv) chemical reactivity.$
Ex 4.21 $d^{4}$
Ex 4.22 $What is meant by 'disproportionation'? Give two examples of disproportionation reaction in aqueous solution.$
Ex 4.23 $+1$
Ex 4.24 $\text{Mn}^{3+}$
Ex 4.25 $Give examples and suggest reasons for the following features of the transition metal chemistry: (i) The lowest oxide of transition metal is basic, the highest is amphoteric/acidic. (ii) A transition metal exhibits highest oxidation state in oxides and fluorides. (iii) The highest oxidation state is exhibited in oxoanions of a metal.$
Ex 4.26 $\text{K}_2\text{Cr}_2\text{O}_7$
Ex 4.27 $What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.$
Ex 4.28 $What are inner transition elements? Decide which of the following atomic numbers are the atomic numbers of the inner transition elements: 29, 59, 74, 95, 102, 104.$
Ex 4.29 $The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.$
Ex 4.30 $Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element.$
Ex 4.31 $\text{Ce}^{3+}$
Ex 4.32 $+4$
Ex 4.33 $Compare the chemistry of the actinoids with that of lanthanoids with reference to: (i) electronic configuration (ii) oxidation states and (iii) chemical reactivity.$
Ex 4.34 $Write the electronic configurations of the elements with the atomic numbers 61, 91, 101, and 109.$
Ex 4.35 $Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following points: (i) electronic configurations (ii) oxidation states (iii) ionisation enthalpies and (iv) atomic sizes.$
Ex 4.36 $3d$
Ex 4.37 $Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.$

Couple	$E^{\circ}$
$\text{Cr}^{2+}/\text{Cr}$	$-0.9\,\text{V}$
$\text{Mn}^{2+}/\text{Mn}$	$-1.2\,\text{V}$
$\text{Fe}^{2+}/\text{Fe}$	$-0.4\,\text{V}$
$\text{Cr}^{3+}/\text{Cr}^{2+}$	$-0.4\,\text{V}$
$\text{Mn}^{3+}/\text{Mn}^{2+}$	$+1.5\,\text{V}$
$\text{Fe}^{3+}/\text{Fe}^{2+}$	$+0.8\,\text{V}$

Ex 4.38

\text{K}_4[\text{Mn}(\text{CN})_6]

Example	Magnetic Moment (BM)
$\text{K}_4[\text{Mn}(\text{CN})_6]$	2.2
$[\text{Fe}(\text{H}_2\text{O})_6]^{2+}$	5.3
$\text{K}_2[\text{MnCl}_4]$	5.9

What the board has asked from this chapter

Questions per paper · 26 papers · 2022 to 2026

Bars average the full papers of each year. 74 further questions come from set variants and are listed below.

2026

36 q

1 $Which of the following is most basic ?$
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General Properties of the Transition Elements (d-Block)
1 $Which property of transition metals enables them to form alloys ?$
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General Properties of the Transition Elements (d-Block)
3 $Which of the following transition metals has lowest enthalpy of atomisation ?$
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General Properties of the Transition Elements (d-Block)
3 $Which of the following is not a transition metal ?$
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Position in the Periodic Table
4 $Actinoids show larger number of oxidation states :$
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The Actinoids
4 $Electronic configuration of chromium is :$
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Electronic Configurations of the d-Block Elements
5 $Manganate ion is paramagnetic due to the presence of :$
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Some Important Compounds of Transition Elements
5 $Which of the following transition metals shows +1 and +2 oxidation states ?$
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General Properties of the Transition Elements (d-Block)
7 $\mathrm{Cr_2O_7^{2-}}$
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Some Important Compounds of Transition Elements
8 $+1$
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General Properties of the Transition Elements (d-Block)
9 $\mathrm{CrO_4^{2-}}$
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Some Important Compounds of Transition Elements
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
13 $Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Zr and Hf have almost identical atomic and ionic radii due to lanthanoid contraction.$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
13 $Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Because Zr and Hf lie in the same group of the periodic table.$
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General Properties of the Transition Elements (d-Block)
For question number 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
14 $Assertion (A) : Zinc, cadmium and mercury are not considered as transition elements. Reason (R) : These elements have completely filled orbitals in their ground state as well as in their common oxidation states.$
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Position in the Periodic Table
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
14 $Assertion (A) : Transition metals show their highest oxidation state with oxygen. Reason (R) : The ability of oxygen to form multiple bonds to metals.$
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General Properties of the Transition Elements (d-Block)
For questions number 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
14 $\mathrm{f^0}$
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The Actinoids
For questions number 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
14 $Assertion (A) : Actinoids show irregularities in their electronic configurations. Reason (R) : In actinoids 5f, 6d and 7s orbitals are of comparable energies.$
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The Actinoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
14 $Assertion (A) : Highest oxidation state of Mn is +7 in first series of transition elements. Reason (R) : Transition metals exhibit variable oxidation states.$
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General Properties of the Transition Elements (d-Block)
For questions number 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
15 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : Actinoids are radioactive in nature.$
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The Actinoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
16 $\mathrm{E^{o}_{Sc^{3+}/Sc^{2+}}}$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
16 $\mathrm{E^{o}_{Mn^{2+}/Mn}}$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
16 $\mathrm{E^{o}_{Cu^{2+}/Cu}}$
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General Properties of the Transition Elements (d-Block)
19 $(a) Why is third ionization enthalpy of manganese very high ? (b) Why Zn, Cd and Hg are not regarded as transition elements ?$
General Properties of the Transition Elements (d-Block)
19 $(a) Why second ionization enthalpies of chromium and copper are exceptionally higher than those of their neighbouring elements ? (b) Why transition elements form interstitial compounds ?$
General Properties of the Transition Elements (d-Block)
19 $(a) First ionization enthalpy of Cr is lower than that of Zn. Why ? (b) Mention any one property of the transition elements which makes them good catalysts.$
General Properties of the Transition Elements (d-Block)
24 $2\mathrm{KMnO_4} \xrightarrow{513\ \mathrm{K}}$
Some Important Compounds of Transition Elements
24 $4\mathrm{FeCr_2O_4} + 8\mathrm{Na_2CO_3} + 7\mathrm{O_2} \longrightarrow$
Some Important Compounds of Transition Elements
24 $2\mathrm{Na_2CrO_4} + 2\mathrm{H^{+}} \longrightarrow$
Some Important Compounds of Transition Elements
31 (a) $\mathrm{Ti^{3+}}$
General Properties of the Transition Elements (d-Block)
31 (a) $\mathrm{Mn_2O_7}$
General Properties of the Transition Elements (d-Block)
31 (b) $(i) A black-brown coloured solid (A) when fused with KOH in the presence of air, produces a dark green coloured compound (B) which on electrolytic oxidation in alkaline medium gives a dark purple coloured compound (C). Identify (A), (B) and (C). Write the reactions involved. (ii) What happens when an acidic solution of the green compound (B) is allowed to stand for some time ? Also write the equation involved. What is this type of reaction called ?$
Some Important Compounds of Transition Elements
31 (b) $\mathrm{E^{o}_{M^{2+}/M}}$
General Properties of the Transition Elements (d-Block)
32 (a) $\mathrm{E^{\circ}}$
General Properties of the Transition Elements (d-Block)
32 (A) $\mathrm{Mn^{2+}}$
General Properties of the Transition Elements (d-Block)
32 (b) $Answer the following questions : (i) Name a member of the lanthanoid series (I) which exhibits +4 oxidation state (II) which exhibits +2 oxidation state. (ii) Why transition metals act as good catalyst ? (iii) Why Cr has higher melting point than Mn ? (iv) What happens when acidic solution of potassium permanganate is allowed to stand for sometime ? Give the equation involved. What is this type of reaction called ?$
General Properties of the Transition Elements (d-Block)
32 (B) $\mathrm{E^{o}_{M^{2+}/M}}$
General Properties of the Transition Elements (d-Block)

$\mathrm{E^{\circ}_{M^{2+}/M}}$	V	Cr	Mn	Fe	Co	Ni	Cu
	$-1.18$	$-0.91$	$-1.18$	$-0.44$	$-0.28$	$-0.25$	$+0.34$

2025

44 q

1 $Which of the following transition metal ion is not coloured ?$
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General Properties of the Transition Elements (d-Block)
1 $With increase in atomic number, the melting point of transition metals :$
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General Properties of the Transition Elements (d-Block)
1 $Among the following outermost electronic configurations of transition metals, which one shows the highest oxidation state ?$
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General Properties of the Transition Elements (d-Block)
2 $\mathrm{Ti^{3+}}$
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General Properties of the Transition Elements (d-Block)
2 $\mathrm{Fe^{3+}}$
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General Properties of the Transition Elements (d-Block)
3 $\mathrm{Cr^{3+}}$
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General Properties of the Transition Elements (d-Block)
4 $\mathrm{KMnO_4}$
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Some Important Compounds of Transition Elements
4 $\mathrm{[Ar]3d^{10}4s^{1}}$
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Electronic Configurations of the d-Block Elements
4 $Which of the following transition metals has the highest melting point ?$
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General Properties of the Transition Elements (d-Block)
5 $Which of the following does not show variable oxidation state ?$
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General Properties of the Transition Elements (d-Block)
5 $Which of the following is the softest metal ?$
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General Properties of the Transition Elements (d-Block)
6 $Out of the following statements, the correct statement is :$
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The Lanthanoids
6 $Out of the following statements, the incorrect statement is :$
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The Lanthanoids
9 $\mathrm{I^{-}}$
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Some Important Compounds of Transition Elements
9 $\mathrm{Cu^{+}}$
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General Properties of the Transition Elements (d-Block)
9 $Which of the following properties of transition metals enables them to behave as catalysts ?$
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General Properties of the Transition Elements (d-Block)
10 $\mathrm{Ti^{3+}}$
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General Properties of the Transition Elements (d-Block)
12 $While doing qualitative analysis in chemistry lab, Abhishek added yellow coloured potassium chromate solution into a test tube. He was surprised to see the colour of the solution changing immediately to orange. He realised that the test tube was not clean and contained a few drops of some liquid. Which of the following substances will be the most likely liquid to be present in the test tube before adding potassium chromate solution ?$
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Some Important Compounds of Transition Elements
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
13 $Assertion (A) : Cuprous salts are diamagnetic. Reason (R) : In cuprous ion, 3d-orbitals are partially filled.$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
13 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : This is due to comparable energies of 5f, 6d and 7s orbitals.$
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The Actinoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
13 $Assertion (A) : Actinoid contraction is greater from element to element than lanthanoid contraction. Reason (R) : Actinoids show wide range of oxidation states.$
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The Actinoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
13 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : Actinoids are radioactive in nature.$
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The Actinoids
For question number 13 to 16, two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
14 $\mathrm{H_2}$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
14 $Assertion (A) : Cuprous salts are diamagnetic. Reason (R) : Cuprous ion has completely filled 3d-orbitals.$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
15 $\mathrm{f^0}$
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The Actinoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
15 $Assertion (A) : First ionisation enthalpy of Cr is lower than that of Zn. Reason (R) : Zinc is a non-transition element.$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
15 $Assertion (A) : Actinoids show irregularities in their electronic configurations. Reason (R) : Actinoids are radioactive in nature.$
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The Actinoids
18 $\mathrm{8MnO_4^{-} + 3S_2O_3^{2-} + H_2O} \longrightarrow$
Some Important Compounds of Transition Elements
18 $\mathrm{FeCr_2O_4}$
Some Important Compounds of Transition Elements
19 $\mathrm{8MnO_4^{-}} + \mathrm{3S_2O_3^{2-}} + \mathrm{H_2O} \longrightarrow$
Some Important Compounds of Transition Elements
18 $\mathrm{2MnO_4^{-}(aq) + 10I^{-}(aq) + 16H^{+}(aq)} \longrightarrow$
Some Important Compounds of Transition Elements
19 $\mathrm{FeCr_2O_4}$
Some Important Compounds of Transition Elements
19 $Examine the following observations : (a) Transition elements generally form coloured compounds. (b) Zinc is not regarded as a transition element.$
General Properties of the Transition Elements (d-Block)
24 $\mathrm{d^4}$
General Properties of the Transition Elements (d-Block)
24 $\mathrm{MnO_4^{-}} + \mathrm{C_2O_4^{2-}} + \mathrm{H^{+}} \longrightarrow$
Some Important Compounds of Transition Elements
24 $\mathrm{E}^{\circ}_{(\mathrm{Mn^{2+}/Mn})}$
General Properties of the Transition Elements (d-Block)
25 $\mathrm{E^{\circ}_{M^{2+}/M}}$
General Properties of the Transition Elements (d-Block)
24 $(\mathrm{d^4})$
General Properties of the Transition Elements (d-Block)
31 (a) $\mathrm{E^{\circ}_{Mn^{2+}/Mn}}$
General Properties of the Transition Elements (d-Block)
31 (b) $\mathrm{KMnO_4}$
General Properties of the Transition Elements (d-Block)
32 (a) $\mathrm{Cr_2O_7^{2-}}$
Some Important Compounds of Transition Elements
32 (b) $\mathrm{V_2O_5}$
General Properties of the Transition Elements (d-Block)
33 (a) $\mathrm{Fe^{2+}}$
Some Important Compounds of Transition Elements
33 (b) $(i) While studying the periodic properties, Arti came across an abnormal behaviour in the atomic size of Hf. She found that, even though Hf is placed below Zr in the same group, both have almost similar atomic sizes. (I) Which phenomenon is responsible for the above behaviour ? Define it. (II) Mention any other consequence of the above phenomenon. (ii) Give reasons for the following : (I) Transition metals exhibit catalytic properties. (II) Transition metals have high enthalpy of atomisation. (III) Sc is a transition element, while Zn is not.$
General Properties of the Transition Elements (d-Block)

2024

33 q

1 $Which of the following does not show variable oxidation states ?$
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General Properties of the Transition Elements (d-Block)
1 $\mathrm{Cr_2O_7^{2-}} \rightleftharpoons 2\mathrm{CrO_4^{2-}}$
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Some Important Compounds of Transition Elements
1 $\mathrm{MnO_2}$
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Some Important Compounds of Transition Elements
1 $Which one of the following first row transition elements is expected to have the highest third ionization enthalpy ?$
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General Properties of the Transition Elements (d-Block)
1 $The most stable oxidation state of Iron is :$
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General Properties of the Transition Elements (d-Block)
1 $The correct order for the increasing oxidizing power in 3d series of transition elements is :$
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General Properties of the Transition Elements (d-Block)
1 $\mathrm{SO_3^{2-}}$
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Some Important Compounds of Transition Elements
3 $\Delta_{\mathrm{a}}\mathrm{H^{o}}$
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General Properties of the Transition Elements (d-Block)
3 $Transition elements form alloys easily because they have :$
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General Properties of the Transition Elements (d-Block)
5 $Transition metals are known to make interstitial compounds. Formation of interstitial compounds makes the transition metal$
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General Properties of the Transition Elements (d-Block)
6 $From the elements of 3d series given below, which element shows the maximum number of oxidation states ?$
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General Properties of the Transition Elements (d-Block)
12 $The general electronic configuration of d-block elements is :$
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Electronic Configurations of the d-Block Elements
For questions number 13 to 16, two statements are given one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below :
13 $Assertion (A) : Zr and Hf are of almost similar atomic radii. Reason (R) : This is due to Lanthanoid contraction.$
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The Lanthanoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
14 $Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Zr and Hf have similar radii due to lanthanoid contraction.$
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The Lanthanoids
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
15 $Assertion (A) : Transition metals have high enthalpy of atomization. Reason (R) : This is because transition metals have low melting points.$
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General Properties of the Transition Elements (d-Block)
For Questions number 13 to 16, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
16 $Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Zr and Hf are radioactive.$
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The Lanthanoids
18 $\mathrm{KMnO_4} \xrightarrow{\text{heat}}$
Some Important Compounds of Transition Elements
19 (a) $What is lanthanoid contraction ? Actinoid contraction is greater from element to element than lanthanoid contraction. Why ?$
The Lanthanoids
19 (b) $Why do transition metals have high enthalpy of atomization ? Which element of 3d-series has lowest enthalpy of atomization ?$
General Properties of the Transition Elements (d-Block)
19 $\mathrm{2MnO_4^{-} + 5SO_3^{2-} + 6H^{+} \longrightarrow}$
Some Important Compounds of Transition Elements
20 $\mathrm{3MnO_4^{2-} + 4H^{+} \longrightarrow}$
Some Important Compounds of Transition Elements
The involvement of $(n-1)d$ electrons in the behaviour of transition elements impart certain distinct characteristics to these elements. Thus, in addition to variable oxidation states, they exhibit paramagnetic behaviour, catalytic properties and tendency for the formation of coloured ions. The transition metals react with a number of non-metals like oxygen, nitrogen and halogens. $\mathrm{KMnO_4}$ and $\mathrm{K_2Cr_2O_7}$ are common examples. The two series of inner transition elements, lanthanoids and actinoids, constitute the f-block of the periodic table. In the lanthanoids, there is regular decrease in atomic size with increase in atomic number due to the imperfect shielding effect of 4f-orbital electrons which causes contraction.
29 (a) $Why do transition metals and their compounds act as good catalysts ?$
General Properties of the Transition Elements (d-Block)
The involvement of $(n-1)d$ electrons in the behaviour of transition elements impart certain distinct characteristics to these elements. Thus, in addition to variable oxidation states, they exhibit paramagnetic behaviour, catalytic properties and tendency for the formation of coloured ions. The transition metals react with a number of non-metals like oxygen, nitrogen and halogens. $\mathrm{KMnO_4}$ and $\mathrm{K_2Cr_2O_7}$ are common examples. The two series of inner transition elements, lanthanoids and actinoids, constitute the f-block of the periodic table. In the lanthanoids, there is regular decrease in atomic size with increase in atomic number due to the imperfect shielding effect of 4f-orbital electrons which causes contraction.
29 (b) $What is the cause of contraction in the atomic size of lanthanoids ?$
The Lanthanoids
The involvement of $(n-1)d$ electrons in the behaviour of transition elements impart certain distinct characteristics to these elements. Thus, in addition to variable oxidation states, they exhibit paramagnetic behaviour, catalytic properties and tendency for the formation of coloured ions. The transition metals react with a number of non-metals like oxygen, nitrogen and halogens. $\mathrm{KMnO_4}$ and $\mathrm{K_2Cr_2O_7}$ are common examples. The two series of inner transition elements, lanthanoids and actinoids, constitute the f-block of the periodic table. In the lanthanoids, there is regular decrease in atomic size with increase in atomic number due to the imperfect shielding effect of 4f-orbital electrons which causes contraction.
29 (c) $Define lanthanoid contraction. How does it affect the atomic radii of the third transition series and the second transition series ?$
The Lanthanoids
The involvement of $(n-1)d$ electrons in the behaviour of transition elements impart certain distinct characteristics to these elements. Thus, in addition to variable oxidation states, they exhibit paramagnetic behaviour, catalytic properties and tendency for the formation of coloured ions. The transition metals react with a number of non-metals like oxygen, nitrogen and halogens. $\mathrm{KMnO_4}$ and $\mathrm{K_2Cr_2O_7}$ are common examples. The two series of inner transition elements, lanthanoids and actinoids, constitute the f-block of the periodic table. In the lanthanoids, there is regular decrease in atomic size with increase in atomic number due to the imperfect shielding effect of 4f-orbital electrons which causes contraction.
29 (c) OR $\mathrm{Cr^{2+}}$
General Properties of the Transition Elements (d-Block)

Transition metals have incomplete d-subshell either in neutral atom or in their ions. The presence of partly filled d-orbitals in their atoms makes transition elements different from that of the non-transition elements. With partly filled d-orbitals, these elements exhibit certain characteristic properties such as display of a variety of oxidation states, formation of coloured ions and entering into complex formation with a variety of ligands. The transition metals and their compounds also exhibit catalytic properties and paramagnetic behaviour. The transition metals are very hard and have low volatility. An examination of the

\mathrm{E^{o}_{M^{2+}/M}}

values shows the varying trends :

	$\mathrm{E^{o}_{M^{2+}/M}}$
V	$-1{\cdot}18$
Cr	$-0{\cdot}91$
Mn	$-1{\cdot}18$
Fe	$-0{\cdot}44$
Co	$-0{\cdot}28$
Ni	$-0{\cdot}25$
Cu	$+0{\cdot}34$
Zn	$-0{\cdot}76$

30 (a)

On what basis can we say that Cu is a transition element but Zn is not ? (Atomic number : Cu = 29, Zn = 30)

General Properties of the Transition Elements (d-Block)

\mathrm{E^{o}_{M^{2+}/M}}

values shows the varying trends :

	$\mathrm{E^{o}_{M^{2+}/M}}$
V	$-1{\cdot}18$
Cr	$-0{\cdot}91$
Mn	$-1{\cdot}18$
Fe	$-0{\cdot}44$
Co	$-0{\cdot}28$
Ni	$-0{\cdot}25$
Cu	$+0{\cdot}34$
Zn	$-0{\cdot}76$

30 (b)

Why do transition elements show variety of oxidation states ?

General Properties of the Transition Elements (d-Block)

\mathrm{E^{o}_{M^{2+}/M}}

values shows the varying trends :

	$\mathrm{E^{o}_{M^{2+}/M}}$
V	$-1{\cdot}18$
Cr	$-0{\cdot}91$
Mn	$-1{\cdot}18$
Fe	$-0{\cdot}44$
Co	$-0{\cdot}28$
Ni	$-0{\cdot}25$
Cu	$+0{\cdot}34$
Zn	$-0{\cdot}76$

30 (c)

\mathrm{E^{o}_{M^{2+}/M}}

General Properties of the Transition Elements (d-Block)

\mathrm{E^{o}_{M^{2+}/M}}

values shows the varying trends :

	$\mathrm{E^{o}_{M^{2+}/M}}$
V	$-1{\cdot}18$
Cr	$-0{\cdot}91$
Mn	$-1{\cdot}18$
Fe	$-0{\cdot}44$
Co	$-0{\cdot}28$
Ni	$-0{\cdot}25$
Cu	$+0{\cdot}34$
Zn	$-0{\cdot}76$

30 (c) OR

\mathrm{d^4}

General Properties of the Transition Elements (d-Block)

31 $\mathrm{E^{\circ}(Mn^{2+}/Mn)}$
General Properties of the Transition Elements (d-Block)
31 $\mathrm{KMnO_4}$
General Properties of the Transition Elements (d-Block)
33 (a) $\mathrm{d^4}$
General Properties of the Transition Elements (d-Block)
33 (b) $\mathrm{Cu_2Cl_2}$
General Properties of the Transition Elements (d-Block)

2023

36 q

2 $Lanthanoid contraction is due to increase in :$
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The Lanthanoids
3 $\mathrm{Cu^{2+}}$
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General Properties of the Transition Elements (d-Block)
4 $The interstitial compounds of transition metals are than the metal itself.$
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General Properties of the Transition Elements (d-Block)
4 $The ions of metals of Group 12 (Zn, Cd and Hg) have completely filled d orbitals and so they :$
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Electronic Configurations of the d-Block Elements
5 $Which property of transition metals enables them to behave as catalysts ?$
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General Properties of the Transition Elements (d-Block)
6 $\mathrm{3d^6}$
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Electronic Configurations of the d-Block Elements
6 $In the two tetrahedral structures of dichromate ion$
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Some Important Compounds of Transition Elements
7 $The most common and stable oxidation state of a Lanthanoid is :$
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The Lanthanoids
11 $\mathrm{KMnO_4}$
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Some Important Compounds of Transition Elements
11 $Among the following outermost configurations of transition metals which one shows the highest oxidation state ?$
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General Properties of the Transition Elements (d-Block)
12 $Which of the following transition metals does not show variable oxidation state ?$
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General Properties of the Transition Elements (d-Block)
12 $Which of the following ions has the maximum number of unpaired d-electrons ? [Atomic number : Fe = 26, V = 23, Ti = 22, Sc = 21]$
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Electronic Configurations of the d-Block Elements
13 $Which of the following characteristics of transition metals is associated with their catalytic activity ?$
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General Properties of the Transition Elements (d-Block)
13 $Which of the following transition metals shows + 1 and + 2 oxidation states ?$
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General Properties of the Transition Elements (d-Block)
14 $Which one among the following metals of 3d series has the lowest melting point ?$
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General Properties of the Transition Elements (d-Block)
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most appropriate answer from the options given below :
17 $Assertion (A) : Transition metals show their highest oxidation state with oxygen. Reason (R) : The ability of oxygen to form multiple bonds to metals.$
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General Properties of the Transition Elements (d-Block)
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most appropriate answer from the options given below :
17 $Assertion (A) : Copper is a non-transition element. Reason (R) : Copper has completely filled d-orbitals in its ground state.$
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Electronic Configurations of the d-Block Elements
For Questions number 15 to 18, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
17 $Assertion (A) : Zr and Hf have almost identical radii. Reason (R) : Both Zr and Hf exhibit similar properties.$
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General Properties of the Transition Elements (d-Block)
For Questions number 15 to 18, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
18 $\mathrm{E}^{\circ}_{\mathrm{Cu}^{2+}/\mathrm{Cu}}$
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General Properties of the Transition Elements (d-Block)
For Questions number 15 to 18, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
18 $\mathrm{Fe^{2+}}$
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General Properties of the Transition Elements (d-Block)
For Questions number 15 to 18, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
18 $Assertion (A) : Manganese shows the highest oxidation state of +7 in 3d series. Reason (R) : Transition metals show variable oxidation states.$
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General Properties of the Transition Elements (d-Block)
Given below are two statements labelled as Assertion (A) and Reason (R). Select the most appropriate answer from the options given below :
18 $Assertion (A) : Transition metals have high enthalpy of atomisation. Reason (R) : Greater number of unpaired electrons in transition metals results in weak metallic bonding.$
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General Properties of the Transition Elements (d-Block)
For Questions number 15 to 18, two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
18 $Assertion (A): Zinc is not regarded as a transition element. Reason (R): In zinc, 3d orbitals are completely filled in its ground state as well as in its oxidised state.$
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Electronic Configurations of the d-Block Elements
21 $\mathrm{E}^{\circ}$
General Properties of the Transition Elements (d-Block)
21 $2\mathrm{MnO_4^{-}} + 5\mathrm{NO_2^{-}} + 6\mathrm{H}^{+} \longrightarrow$
Some Important Compounds of Transition Elements
33 (a) $\mathrm{E^o}$
General Properties of the Transition Elements (d-Block)
33 (a) $\mathrm{E}^{\circ}_{\mathrm{Mn}^{2+}/\mathrm{Mn}}$
General Properties of the Transition Elements (d-Block)
33 (b) $\mathrm{Cr_2O_7^{2-}} + 14\mathrm{H}^{+} + 6\mathrm{Fe}^{2+} \longrightarrow$
Some Important Compounds of Transition Elements
33 (b) $\mathrm{Ce^{4+}}$
The Lanthanoids
34 $\mathrm{Cr}^{2+}$
General Properties of the Transition Elements (d-Block)
34 $\mathrm{E}^{\circ}_{\mathrm{M}^{2+}/\mathrm{M}}$
General Properties of the Transition Elements (d-Block)
34 (a) $\mathrm{Zn}^{2+}$
General Properties of the Transition Elements (d-Block)
34 (b) $\mathrm{K_2Cr_2O_7}$
Some Important Compounds of Transition Elements
35 $3\,\mathrm{MnO_4^{2-}} + 4\mathrm{H^{+}} \rightarrow$
General Properties of the Transition Elements (d-Block)
35 $\mathrm{4s^2\ 3d^3}$
General Properties of the Transition Elements (d-Block)
35 $\mathrm{Cr^{3+}}$
General Properties of the Transition Elements (d-Block)

2022

23 q

4 $\mathrm{Cu^{2+}}$
General Properties of the Transition Elements (d-Block)
4 $\mathrm{Cr^{2+}}$
General Properties of the Transition Elements (d-Block)
4 $\mathrm{E^\circ}$
General Properties of the Transition Elements (d-Block)
4 $\mathrm{Ti^{4+}}$
General Properties of the Transition Elements (d-Block)
6 $\mathrm{Ti^{4+}}$
General Properties of the Transition Elements (d-Block)
7 $(a) Write any two consequences of Lanthanoid Contraction. (b) Name the element of 3d series which exhibits the largest number of oxidation states. Give reason.$
The Lanthanoids
7 $What is Lanthanoid contraction ? What is the cause of Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.$
The Lanthanoids
8 $\mathrm{E^{o}_{(Mn^{2+}/Mn)}}$
General Properties of the Transition Elements (d-Block)
8 $Define transition metals. Why Zn, Cd and Hg are not called transition metals ? How is the variability in oxidation states of transition metals different from that of p-block elements ?$
General Properties of the Transition Elements (d-Block)
8 $Give reasons for the following statements : (a) Copper does not displace hydrogen from acids. (b) Transition metals and most of their compounds show paramagnetic behaviour. (c) Zn, Cd and Hg are soft metals.$
General Properties of the Transition Elements (d-Block)
8 (a) $\mathrm{E^{o}_{M^{2+}/M}}$
General Properties of the Transition Elements (d-Block)
8 $\mathrm{[Ti(H_2O)]^{3+}}$
General Properties of the Transition Elements (d-Block)
8 (b) $Define transition elements. Which of the d-block elements may not be regarded as the transition elements ? Why transition metals generally form coloured compounds ?$
General Properties of the Transition Elements (d-Block)
8 $\mathrm{V^{3+}}$
General Properties of the Transition Elements (d-Block)
8 (a) $Account for the following : (i) Zr and Hf have almost similar atomic radii. (ii) Transition metals show variable oxidation states. (iii) Zinc has lowest enthalpy of atomisation.$
General Properties of the Transition Elements (d-Block)
8 (b) $Why transition metals and their compounds act as good catalyst ? How is the variability in oxidation states of transition metals different from that of the non-transition metals ? Illustrate with examples.$
General Properties of the Transition Elements (d-Block)

\mathrm{E}^{\ominus}_{\mathrm{M^{2+}/M}}

$\mathrm{E}^{\ominus}_{\mathrm{M^{2+}/M}}$	Cr	Mn	Fe	Co	Ni	Cu	Zn
	$-\,0{\cdot}91$	$-\,1{\cdot}18$	$-\,0{\cdot}44$	$-\,0{\cdot}28$	$-\,0{\cdot}25$	$+\,0{\cdot}34$	$-\,0{\cdot}76$

General Properties of the Transition Elements (d-Block)

10 $\mathrm{Ti^{2+}}$
General Properties of the Transition Elements (d-Block)
11 (a) $\mathrm{Eu^{2+}}$
General Properties of the Transition Elements (d-Block)
11 (a) $\mathrm{E}^{\ominus}_{\mathrm{M^{2+}/M}}$
General Properties of the Transition Elements (d-Block)
11 (b) $Answer the following questions on the basis of the figure given below : (i) Which element in 3d series has lowest enthalpy of atomisation ? (ii) Why do metals of the second and third series have greater enthalpies of atomisation ? (iii) Why are enthalpies of atomisation of transition metals quite high ?$
General Properties of the Transition Elements (d-Block)
11 (b) $What is Lanthanoid contraction ? Write two consequences of Lanthanoid contraction.$
The Lanthanoids
11 $Account for the following : (i) Transition metals and their compounds show catalytic activities. (ii) Zn, Cd and Hg are non-transition elements. (iii) Zr and Hf are of almost identical atomic radii.$
General Properties of the Transition Elements (d-Block)

The 10 board questions to practise first

The questions the board asked again come first, most asked first. Each one says how often and when.

Question 1
Asked 3 times: 2023, 2024, 2025
5 $Which of the following does not show variable oxidation state ?$
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Question 2
Asked 2 times: 2023, 2026
8 $+1$
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Question 3
Asked 2 times: 2024*, 2026 (* = numbers or wording changed that year)
3 $Which of the following transition metals has lowest enthalpy of atomisation ?$
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Question 4
Asked 2 times: 2024, 2026
1 $Which property of transition metals enables them to form alloys ?$
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Question 5
Asked 2 times: 2023, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
14 $Assertion (A) : Transition metals show their highest oxidation state with oxygen. Reason (R) : The ability of oxygen to form multiple bonds to metals.$
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Question 6
Asked 2 times: 2023, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
14 $Assertion (A) : Highest oxidation state of Mn is +7 in first series of transition elements. Reason (R) : Transition metals exhibit variable oxidation states.$
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Question 7
Asked 2 times: 2023, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
16 $\mathrm{E^{o}_{Cu^{2+}/Cu}}$
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Question 8
Asked 2 times: 2023, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
14 $Assertion (A) : Zinc, cadmium and mercury are not considered as transition elements. Reason (R) : These elements have completely filled orbitals in their ground state as well as in their common oxidation states.$
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Question 9
Asked 2 times: 2024, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
13 $Assertion (A) : Separation of Zr and Hf is difficult. Reason (R) : Zr and Hf have almost identical atomic and ionic radii due to lanthanoid contraction.$
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Question 10
Asked 2 times: 2025, 2026
Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the options given below.
15 $Assertion (A) : Actinoids show wide range of oxidation states. Reason (R) : Actinoids are radioactive in nature.$
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Worked Examples

Solved Examples

Intext Questions

Exercises

What the board has asked from this chapter

2026

2025

2024

2023

2022

The 10 board questions to practise first

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10