List of top Chemistry Questions on Some Applications of d- and f-Block Elements asked in CBSE CLASS XII

Why is \( Cr^{2+} \) strongly reducing while \( Mn^{3+} \) is strongly oxidizing?
Out of Fe$^{3+}$, Sc$^{3+}$, Cr$^{3+}$ and Co$^{3+}$ ions, the one which is colourless in aqueous solution is:
Assertion (A): Cuprous salts are diamagnetic.
Reason (R): Cuprous ion has completely filled 3d-orbitals.
Give explanation for each of the following observations:
(a) With the same d$^8$ orbital configuration, Mn$^{2+}$ ion is an oxidizing agent whereas Cr$^{2+}$ ion is a reducing agent.
(b) Atomic contraction is greater from element to element than much from lanthanides.
(c) Transition metals form large number of interstitial compounds with H, B, C, and N.
Examine the following observations: (a) Transition elements generally form coloured compounds.
(b) Zinc is not regarded as a transition element.
The element having [Ar]$3d^{10}4s^1$ electronic configuration is
Which element of the 3d series has the lowest enthalpy of atomisation and why?
Write two consequences of lanthanide contraction.
When \( \text{FeCr}_2\text{O}_4 \) is fused with \( \text{Na}_2\text{CO}_3 \) in the presence of air, it gives a yellow solution of compound (A). Compound (A) on acidification gives compound (B). Compound (B) on reaction with KCl forms an orange-colored compound (C). An acidified solution of compound (C) oxidizes \( \text{Na}_2\text{SO}_3 \) to (D). Identify (A), (B), (C), and (D).
The element having \([Ar]3d^{10}4s^1\) electronic configuration is
The elements of 3d transition series are given as: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn
Answer the following:
When MnO\(_2\) is fused with KOH in air, it gives:
Why Zinc is not regarded as a transition element?
Account for the following : The melting and boiling points of Zn, Cd, and Hg are low.
Assertion (A): Transition metals have high enthalpy of atomization. Reason (R): This is because transition metals have low melting points.
Why do transition metals have high enthalpy of atomization? Which element of the 3d-series has the lowest enthalpy of atomization?
What is lanthanoid contraction? Actinoid contraction is greater from element to element than lanthanoid contraction. Why?
Transition metals have incomplete d-subshells either in the neutral atom or in their ions. The presence of partly filled d-orbitals in their atoms makes transition elements different from 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
  • 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 E0 M2+/M values shows the varying trends:
Transition metals have incomplete d-subshell