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The d- and f-Block Elements — NEET & JEE MCQs with answers
The d-block (transition metals, groups 3–12) and f-block (lanthanoids and actinoids) are characterised by progressive filling of d and f orbitals respectively. Transition metals exhibit variable oxidation states, high melting points, catalytic activity, formation of coloured ions and complex compounds. Lanthanoids show lanthanoid contraction; actinoids show greater variability in oxidation states and radioactivity.
Topics in this chapter
- 4.1 Position in the Periodic Table
- 4.2 Electronic Configurations of the d-Block Elements
- 4.3 General Properties of the Transition Elements (d-Block)
- 4.4 Some Important Compounds of Transition Elements
- 4.5 The Lanthanoids
- 4.6 The Actinoids
- 4.7 Some Applications of d- and f-Block Elements
Free practice questions
The balanced equation for the liberation of iodine from potassium iodide by acidified permanganate is
- A. $\mathrm{10\,I^- + 2\,MnO_4^- + H_2O \rightarrow 2\,MnO_2 + 5\,I_2 + 2\,OH^-}$
- B. $\mathrm{10\,I^- + 2\,MnO_4^- + 16\,H^+ \rightarrow 2\,Mn^{2+} + 8\,H_2O + 5\,I_2}$
- C. $\mathrm{10\,I^- + 2\,MnO_4^- + 8\,H^+ \rightarrow 2\,Mn^{2+} + 8\,H_2O + 5\,I_2}$
- D. $\mathrm{6\,I^- + 2\,MnO_4^- + 16\,H^+ \rightarrow 2\,Mn^{2+} + 8\,H_2O + 3\,I_2}$
Show answer
Answer: B — Option B is correct; it is the NCERT equation and it balances for mass and charge (left $-10 - 2 + 16 = +4$; right $+4$). Two permanganate ions accept $10$ electrons and $10$ iodide ions supply exactly $10$.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.4 ("(a) Iodine is liberated from potassium iodide :")
How is an alloy defined in NCERT?
- A. A compound formed when small atoms are trapped in a metal lattice
- B. A blend of metals prepared by mixing the components
- C. A complex species formed when a metal ion binds neutral molecules
- D. A non stoichiometric oxide of a transition metal
Show answer
Answer: B — NCERT defines an alloy as a blend of metals prepared by mixing the components. Hence option **B** is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.3.14 ("An alloy is a blend of metals prepared by mixing the components.")
In which respect do the actinoids resemble the lanthanoids as regards their compounds?
- A. They have more compounds in the $+3$ state than in the $+4$ state
- B. They form compounds only in the $+2$ state
- C. They form no compounds in the $+3$ state at all
- D. They have more compounds in the $+4$ state than in the $+3$ state
Show answer
Answer: A — The text says the actinoids resemble the lanthanoids in having more compounds in the $+3$ state than in the $+4$ state, though both kinds of ion tend to hydrolyse. Hence option A is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.6 ("4.11). The actinoids resemble the lanthanoids in having more compounds")
In Table 4.9, the electronic configurations quoted for the lanthanoids show only the electrons outside which core?
- A. $[\mathrm{Kr}]$
- B. $[\mathrm{Xe}]$
- C. $[\mathrm{Rn}]$
- D. $[\mathrm{Ar}]$
Show answer
Answer: B — The footnote to Table 4.9 reads that only electrons outside the $[\mathrm{Xe}]$ core are indicated. $[\mathrm{Rn}]$ is used for the actinoid configurations quoted later in the chapter, while $[\mathrm{Kr}]$ and $[\mathrm{Ar}]$ belong to earlier periods. Hence option B is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.5 ("* Only electrons outside [Xe] core are indicated")
Which sets of orbitals are described in the chapter as relatively more stable?
- A. Completely empty sets of orbitals only
- B. Sets of orbitals containing a single electron only
- C. Half and completely filled sets of orbitals
- D. Sets of orbitals that are just over half filled
Show answer
Answer: C — The chapter states that half and completely filled sets of orbitals are relatively more stable, and this is the factor reflected in the configurations of Cr and Cu. Hence option C is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 §4.2 ("half and completely filled sets of orbitals are relatively more stable. A")
Catalysts of which metal enable the hydrogenation of fats to proceed?
- A. Nickel
- B. Vanadium
- C. Iron
- D. Palladium
Show answer
Answer: A — The text says nickel catalysts enable the hydrogenation of fats to proceed. Iron serves the Haber process and palladium, as $\mathrm{PdCl_2}$, the Wacker process. Hence option A is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.7 ("Nickel catalysts enable the hydrogenation of fats to proceed. In the Wacker")
According to the NCERT text, the d-block of the periodic table contains the elements of which groups?
- A. Groups 3–12
- B. Groups 1–2
- C. Groups 13–18
- D. Groups 3–11
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Answer: A — The text opens by stating that the d-block of the periodic table contains the elements of the groups 3-12 in which the d orbitals are progressively filled. Groups 1–2 make up the s-block and groups 13–18 the p-block, while restricting the count to groups 3–11 would wrongly leave out group 12 (Zn, Cd, Hg, Cn), which the book does place inside the d-block. Hence option A is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 §4.1 ("of the groups 3-12 in which the d orbitals are")
How many moles of permanganate ion are formed from $3$ mol of manganate ion in the acid disproportionation?
- A. $1$
- B. $1.5$
- C. $3$
- D. $2$
Show answer
Answer: D — Option D is correct. The NCERT equation is $\mathrm{3\,MnO_4^{2-} + 4\,H^+ \rightarrow 2\,MnO_4^- + MnO_2 + 2\,H_2O}$: two of the three manganese centres are oxidised to $+7$ and one is reduced to $+4$. Charge check: $-6 + 4 = -2$ on both sides.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.4 ("For example, manganese (VI) becomes unstable relative to manganese(VII) and")
Between which two elements does NCERT note a significant increase in density in the first transition series?
- A. From scandium $(Z = 21)$ to manganese $(Z = 25)$
- B. From vanadium $(Z = 23)$ to zinc $(Z = 30)$
- C. From titanium $(Z = 22)$ to copper $(Z = 29)$
- D. From scandium $(Z = 21)$ to zinc $(Z = 30)$
Show answer
Answer: C — The text says that from titanium $(Z = 22)$ to copper $(Z = 29)$ the significant increase in the density may be noted (Table $4.2$). Hence option **C** is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 · §4.3.2 ("from titanium (Z = 22) to copper (Z = 29) the")
Which of the following is NOT among the characteristic properties the chapter links to partly filled d orbitals?
- A. Display of a variety of oxidation states
- B. Formation of coloured ions
- C. Complete absence of paramagnetic behaviour
- D. Entering into complex formation with a variety of ligands
Show answer
Answer: C — The chapter lists a variety of oxidation states, coloured ions and complex formation with a variety of ligands, and it adds that transition metals and their compounds also exhibit paramagnetic behaviour. An absence of paramagnetic behaviour therefore contradicts the text. Hence option C is correct.
NCERT Class 12 Chemistry Part-1 · Ch 4 §4.2 ("filled d orbitals these elements exhibit certain characteristic properties")
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