Appeared in: 2026 (2 sets)
(a) (i) Account for the following :
(I) $\text{MnO}$ is basic while $\text{Mn}_2\text{O}_7$ is acidic.
(II) Iron has higher enthalpy of atomization than that of copper.
(III) $\text{Mn}^{3+}$ is a stronger oxidising agent than $\text{Cr}^{3+}$.
(ii) How do you prepare potassium dichromate from sodium chromate ? Write balanced chemical equation for each step.
OR
(b) Answer the following questions :
(i) Why is chemistry of actinoids more complicated as compared to lanthanoids ?
(ii) $E^\circ_{\text{M}^{2+}/\text{M}}$ values are not regular for first row transition elements ($3\text{d}$ series). Why ?
(iii) Identify the following :
(I) Oxoanion of chromium which is stable in acidic medium.
(II) The lanthanoid element that exhibits $+4$ oxidation state.
(iv) Write the products obtained on heating $\text{KMnO}_4$.
(v) Predict which of the following ions will be coloured in aqueous solution :
$\text{Cu}^+, \text{Sc}^{3+}, \text{Fe}^{2+}, \text{Ti}^{3+}, \text{Zn}^{2+}$