Predict which of the following will be coloured in aqueous solution and why?
\(Sc^{3+}, Fe^{3+}, Zn^{2+}\)
[Atomic numbers: Sc = 21, Fe = 26, Zn = 30]
\(Sc^{3+}, Fe^{3+}, Zn^{2+}\)
[Atomic numbers: Sc = 21, Fe = 26, Zn = 30]
Solution and Explanation
Among the given ions, Fe3+ is coloured in aqueous solution because it has unpaired electrons in its d-orbital, which allows d-d transitions.
On the other hand:
- Sc3+ has an empty d-orbital (d0 configuration), so no d-d transition occurs → Colourless.
- Zn2+ has a fully filled d-orbital (d10 configuration), so no d-d transition occurs → Colourless.
Top Questions on Transition Elements
- Explain why transition metals show variable oxidation states.
- WBBSE XII - 2026
- Chemistry
- Transition Elements
- Out of the following statements, the incorrect statement is:
- CBSE CLASS XII - 2025
- Chemistry
- Transition Elements
Give explanation for each of the following observations:
(a) With the same d-orbital configuration (d4), Mn3+ ion is an oxidizing agent whereas Cr2+ ion is a reducing agent.
(b) Actinoid contraction is greater from element to element than that among lanthanoids.
(c) Transition metals form a large number of interstitial compounds with H, B, C, and N.
- CBSE CLASS XII - 2025
- Chemistry
- Transition Elements
- For the second and third row of transition elements, which statement is not true?
- CUET (PG) - 2025
- Chemistry
- Transition Elements
A transition metal (M) among Mn, Cr, Co and Fe has the highest standard electrode potential \( (M^{3+} / M^{2+}) \). It forms a metal complex of the type \( [M(CN)_6]^{4-} \). The number of electrons present in the \( e_g \) orbital of the complex is ________.
- JEE Main - 2025
- Chemistry
- Transition Elements
Questions Asked in CBSE CLASS XII exam
- Find the general solution of the differential equation \[ y\log y\,\frac{dx}{dy}+x=\frac{2}{y}. \]
- CBSE CLASS XII - 2026
- Differential Equations
- A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of 60° in 0.2 s. The value of emf induced in the loop will be:
- CBSE CLASS XII - 2026
- Electromagnetic induction
A racing track is built around an elliptical ground whose equation is given by \[ 9x^2 + 16y^2 = 144 \] The width of the track is \(3\) m as shown. Based on the given information answer the following:
(i) Express \(y\) as a function of \(x\) from the given equation of ellipse.
(ii) Integrate the function obtained in (i) with respect to \(x\).
(iii)(a) Find the area of the region enclosed within the elliptical ground excluding the track using integration.
OR
(iii)(b) Write the coordinates of the points \(P\) and \(Q\) where the outer edge of the track cuts \(x\)-axis and \(y\)-axis in first quadrant and find the area of triangle formed by points \(P,O,Q\).
- CBSE CLASS XII - 2026
- Integration
- Consider a cylindrical conductor of length \( l \) and area of cross-section \( A \). Current \( I \) is maintained in the conductor and electrons drift with velocity \( \vec{v}_d \, (|\vec{v}_d| = \frac{eE}{m} \tau) \), where symbols have their usual meanings. Show that the conductivity of the material of the conductor is given by \[ \sigma = \frac{n e^2 \tau}{m}. \]
- CBSE CLASS XII - 2026
- Current Density
- The painting Hazrat Nizamuddin Auliya and Amir Khusro belongs to which sub-school of Deccan Miniature?
- CBSE CLASS XII - 2026
- Indian Miniature Paintings and Museums