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JKCET d- and f-Block Elements — practice questions

Explore 54 free d- and f-Block Elements questions in JKCET Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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d- and f-Block Elements questions and exercises with answers

Showing questions 1–30 of 54.

The general outer electronic configuration of d-block elements is:Read the answer and worked solution →The electronic configuration of Cr (Z = 24) is:Read the answer and worked solution →Which 3d transition element exhibits the largest number of oxidation states?Read the answer and worked solution →The most stable oxidation state of Sc is:Read the answer and worked solution →The spin-only magnetic moment μ in BM for n unpaired electrons is given by:Read the answer and worked solution →Calculate the spin-only magnetic moment of a divalent ion of Mn (Z = 25):Read the answer and worked solution →Which of the following ions is colourless and diamagnetic?Read the answer and worked solution →The oxidation state of chromium in both CrO₄²⁻ and Cr₂O₇²⁻ is:Read the answer and worked solution →Potassium dichromate (K₂Cr₂O₇) is prepared from which ore?Read the answer and worked solution →In KMnO₄, the oxidation state of Mn is:Read the answer and worked solution →The most common oxidation state of lanthanoids is:Read the answer and worked solution →Which lanthanoid is well known to exhibit the +4 oxidation state in aqueous solution as a strong oxidising agent?Read the answer and worked solution →The general electronic configuration of actinoids is:Read the answer and worked solution →Which of the following ions is NOT coloured in aqueous solution?Read the answer and worked solution →Among Sc²⁺, V³⁺, Mn²⁺ and Zn²⁺, which is paramagnetic with **5** unpaired electrons?Read the answer and worked solution →d-block elements have differentiating electrons in:Read the answer and worked solution →f-block elements include:Read the answer and worked solution →Compounds of transition metals are usually:Read the answer and worked solution →Why does Zn²⁺ have no color (Zn = d¹⁰)?Read the answer and worked solution →Which transition metal forms unstable highest oxidation state +7?Read the answer and worked solution →Magnetic moment of complex with 5 unpaired d-electrons (high spin):Read the answer and worked solution →K₂Cr₂O₇ (potassium dichromate) is a strong:Read the answer and worked solution →Coordination number of Ag in [Ag(CN)₂]⁻:Read the answer and worked solution →Oxidation state of Cu in [Cu(NH₃)₄]²⁺:Read the answer and worked solution →Magnetic moment of [Fe(H₂O)₆]³⁺ (Fe³⁺ is d⁵, weak field H₂O → high spin):Read the answer and worked solution →Number of unpaired electrons in [Mn(CN)₆]³⁻ (Mn(III), d⁴, strong field CN⁻):Read the answer and worked solution →Eu²⁺ is more stable than other Ln²⁺ because:Read the answer and worked solution →Why is Sc³⁺ colorless?Read the answer and worked solution →Magnetic susceptibility of Fe³⁺ vs Fe²⁺ in high-spin complexes:Read the answer and worked solution →NEET · Chemistry · Lanthanide or ActinideRead the answer and worked solution →

Worked practice questions

The general outer electronic configuration of d-block elements is:

  1. nd¹⁻¹⁰ (n+1)s¹⁻²
  2. (n−1)d⁰ ns²
  3. (n−1)d¹⁻¹⁰ ns¹⁻²
  4. ns¹⁻² np¹⁻⁶
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Correct answer: C. (n−1)d¹⁻¹⁰ ns¹⁻²

**(n−1)d¹⁻¹⁰ ns¹⁻²** (except Pd, 4d¹⁰5s⁰). The penultimate d orbital is progressively filled across each row ns has 1–2 electrons.

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The electronic configuration of Cr (Z = 24) is:

  1. [Ar] 3d³ 4s³
  2. [Ar] 3d⁵ 4s¹
  3. [Ar] 3d⁶ 4s⁰
  4. [Ar] 3d⁴ 4s²
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Correct answer: B. [Ar] 3d⁵ 4s¹

**Cr: [Ar] 3d⁵ 4s¹** (not 3d⁴ 4s²). The half-filled 3d⁵ + half-filled 4s¹ configuration provides **extra stability** from exchange energy and symmetry. **Similar exception in Cu:** 3d¹⁰ 4s¹ (not 3d⁹ 4s²).

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Which 3d transition element exhibits the largest number of oxidation states?

  1. Zn (only +2)
  2. Sc (only +3)
  3. Fe (+2 and +3)
  4. Mn — +2, +3, +4, +5, +6, +7 (six states; widest range)
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Correct answer: D. Mn — +2, +3, +4, +5, +6, +7 (six states; widest range)

**Manganese** exhibits the **widest range of oxidation states (+2 to +7)** in the 3d series. This is because Mn has 7 (3d⁵ 4s²) valence electrons available and is in the middle of the series. The early (Sc, Ti) and late (Cu, Zn) members have fewer states.

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More Chemistry topics

Ideal and Non-Ideal SolutionsIdeal SolutionsNon-Ideal SolutionsReactions in Aqueous SolutionElectrochemistryElectrochemical SeriesSolutionsCoordination Compounds