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The d- and f-Block Elements: questions with answers

Class 12 Chemistry, Chapter 4 (NCERT). 15 questions by concept. Open “Show answer” for the answer and why.

How to teach this chapter · Common misconceptions & worked visual for this chapter

Position and electronic configuration of d-block elements

Question 1

Which statement gives the sound Class XII chemistry for ‘Position and electronic configuration of d-block elements’?

  1. (a)Only the name of the substance is needed for position and electronic configuration of d-block elements; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  2. (b)For position and electronic configuration of d-block elements, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.
  4. (d)The same conclusion about position and electronic configuration of d-block elements remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
Show answer

(c) Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Question 2

Which principle should be retained when checking an inference about ‘Position and electronic configuration of d-block elements’?

  1. (a)The same conclusion about position and electronic configuration of d-block elements remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.
  3. (c)Only the name of the substance is needed for position and electronic configuration of d-block elements; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  4. (d)For position and electronic configuration of d-block elements, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
Show answer

(b) Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Question 3

Which statement correctly governs a new case involving position and electronic configuration of d-block elements?

  1. (a)Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.
  2. (b)For position and electronic configuration of d-block elements, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)The same conclusion about position and electronic configuration of d-block elements remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  4. (d)Only the name of the substance is needed for position and electronic configuration of d-block elements; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
Show answer

(a) Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Transition elements have atoms or common ions with incomplete d subshells. Their general configurations reflect the close energies of ns and (n−1)d orbitals, with recognised stability exceptions such as Cr and Cu.

Physical properties and variable oxidation states

Question 4

Which statement gives the sound Class XII chemistry for ‘Physical properties and variable oxidation states’?

  1. (a)Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.
  2. (b)Only the name of the substance is needed for physical properties and variable oxidation states; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  3. (c)For physical properties and variable oxidation states, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  4. (d)The same conclusion about physical properties and variable oxidation states remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
Show answer

(a) Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.

Partly filled d orbitals and strong metallic bonding support high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying, with trends interpreted through electronic configuration.

Question 5

Which principle should be retained when checking an inference about ‘Physical properties and variable oxidation states’?

  1. (a)Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.
  2. (b)For physical properties and variable oxidation states, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)The same conclusion about physical properties and variable oxidation states remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  4. (d)Only the name of the substance is needed for physical properties and variable oxidation states; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
Show answer

(a) Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.

Partly filled d orbitals and strong metallic bonding support high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying, with trends interpreted through electronic configuration.

Question 6

Which statement survives a structure, equation, reagent, and condition audit for physical properties and variable oxidation states?

  1. (a)Only the name of the substance is needed for physical properties and variable oxidation states; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  2. (b)The same conclusion about physical properties and variable oxidation states remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  3. (c)Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.
  4. (d)For physical properties and variable oxidation states, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
Show answer

(c) Partly filled d orbitals and strong metallic bonding lead to high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying. Electronic configuration explains these trends.

Partly filled d orbitals and strong metallic bonding support high enthalpies, melting points, variable oxidation states, coloured ions, paramagnetism, complex formation, catalysis, and alloying, with trends interpreted through electronic configuration.

Potassium dichromate chemistry

Question 7

Which statement gives the sound Class XII chemistry for ‘Potassium dichromate chemistry’?

  1. (a)The same conclusion about potassium dichromate chemistry remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.
  3. (c)For potassium dichromate chemistry, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  4. (d)Only the name of the substance is needed for potassium dichromate chemistry; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
Show answer

(b) Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Question 8

Which principle should be retained when checking an inference about ‘Potassium dichromate chemistry’?

  1. (a)Only the name of the substance is needed for potassium dichromate chemistry; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  2. (b)For potassium dichromate chemistry, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.
  4. (d)The same conclusion about potassium dichromate chemistry remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
Show answer

(c) Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Question 9

Which statement correctly governs a new case involving potassium dichromate chemistry?

  1. (a)Only the name of the substance is needed for potassium dichromate chemistry; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  2. (b)Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.
  3. (c)The same conclusion about potassium dichromate chemistry remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  4. (d)For potassium dichromate chemistry, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
Show answer

(b) Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Dichromate–chromate equilibria depend on pH, and acidified dichromate is a strong oxidising agent reduced from Cr(VI) to Cr(III). Equations must preserve oxygen, hydrogen, charge, and the reaction medium.

Potassium permanganate chemistry

Question 10

Which statement gives the sound Class XII chemistry for ‘Potassium permanganate chemistry’?

  1. (a)The same conclusion about potassium permanganate chemistry remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.
  3. (c)Only the name of the substance is needed for potassium permanganate chemistry; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  4. (d)For potassium permanganate chemistry, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
Show answer

(b) Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.

Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.

Question 11

Which principle should be retained when checking an inference about ‘Potassium permanganate chemistry’?

  1. (a)For potassium permanganate chemistry, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  2. (b)The same conclusion about potassium permanganate chemistry remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  3. (c)Only the name of the substance is needed for potassium permanganate chemistry; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  4. (d)Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.
Show answer

(d) Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.

Permanganate is strongly oxidising, but its reduction product depends on medium: Mn2+ in acid, MnO2 in neutral or weakly alkaline conditions, and manganate in strongly alkaline medium.

Actinoids and comparison with lanthanoids

Question 12

Which statement gives the sound Class XII chemistry for ‘Actinoids and comparison with lanthanoids’?

  1. (a)The same conclusion about actinoids and comparison with lanthanoids remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.
  3. (c)For actinoids and comparison with lanthanoids, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  4. (d)Only the name of the substance is needed for actinoids and comparison with lanthanoids; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
Show answer

(b) Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.

Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.

Question 13

Which principle should be retained when checking an inference about ‘Actinoids and comparison with lanthanoids’?

  1. (a)The same conclusion about actinoids and comparison with lanthanoids remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)Only the name of the substance is needed for actinoids and comparison with lanthanoids; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  3. (c)Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.
  4. (d)For actinoids and comparison with lanthanoids, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
Show answer

(c) Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.

Actinoids fill 5f orbitals, are radioactive, and show a wider range of oxidation states than lanthanoids because 5f, 6d, and 7s energies are comparable. Actinoid contraction parallels but is generally less regular than lanthanoid contraction.

Lanthanoids and lanthanoid contraction

Question 14

Which statement gives the sound Class XII chemistry for ‘Lanthanoids and lanthanoid contraction’?

  1. (a)Only the name of the substance is needed for lanthanoids and lanthanoid contraction; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  2. (b)For lanthanoids and lanthanoid contraction, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)The same conclusion about lanthanoids and lanthanoid contraction remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  4. (d)Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.
Show answer

(d) Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.

Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.

Question 15

Which principle should be retained when checking an inference about ‘Lanthanoids and lanthanoid contraction’?

  1. (a)The same conclusion about lanthanoids and lanthanoid contraction remains valid after changing the reagent, molecular structure, medium, or condition that controls the result.
  2. (b)For lanthanoids and lanthanoid contraction, the relevant direction, trend, product ordering, or cause-and-effect relation is always the exact reverse of the governing rule.
  3. (c)Only the name of the substance is needed for lanthanoids and lanthanoid contraction; equations, structures, stoichiometry, evidence, and conditions cannot change the answer.
  4. (d)Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.
Show answer

(d) Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.

Lanthanoids mainly show +3 oxidation state. Poor shielding by 4f electrons causes a steady size decrease across the series, explaining similar chemistry, difficult separation, and close radii of corresponding 4d and 5d elements.

Common misconception in The d- and f-Block Elements

Open full misconception guide →

Is every d-block element a transition element?

Wrong

Zinc is a transition element because it sits in the d block.

Why it feels right. I use block membership as the definition.

Right

The usual school definition requires an incomplete d subshell in the atom or a cation it forms.

Worked example

Zn and Zn²⁺ · d¹⁰
↑↓
↑↓
↑↓
↑↓
↑↓
Fe²⁺ · d⁶
↑↓
↑
↑
↑
↑
Each box is a d orbital. The zinc examples have filled d subshells, while Fe²⁺ has an incomplete one.
  1. Zn has a filled 3d¹⁰ subshell and Zn²⁺ also has 3d¹⁰.
  2. Fe²⁺ has 3d⁶, so iron satisfies the criterion and zinc does not.