The Lanthanoid ion which would form coloured compounds is -------------.
Atomic numbers: $$\mathrm{Yb}=70, \quad \mathrm{Lu}=71, \mathrm{Pr}=59, \quad \mathrm{La}=57$$
Given below are 4 statements. Two of these are correct statements. Identify them.
A. $$\mathrm{Co}^{2+}$$ is easily oxidised to $$\mathrm{Co}^{3+}$$ in the presence of a strong ligand like $$\mathrm{CN}^{-}$$
B. $$[\mathrm{Fe}(\mathrm{CN})_6]^{4-}$$ is an octahedral complex ion which is paramagnetic in nature.
C. Removal of $$\mathrm{H}_2 \mathrm{O}$$ molecules from $$[\mathrm{Ti}(\mathrm{H}_2 \mathrm{O})_6] \mathrm{Cl}_3$$ on strong heating converts it to a colourless compound.
D. Crystal Field splitting in Octahedral and Tetrahedral complexes is given by the equation $$\Delta_0=4 / 9 \Delta_t$$
The Enthalpy of combustion of $$\mathrm{C}_6 \mathrm{H}_5 \mathrm{COOH}(\mathrm{s})$$ at $$25^{\circ} \mathrm{c}$$ and 1.0 atm pressure is $$-2546 \mathrm{~kJ} / \mathrm{mol}$$. What is the Internal energy change for this reaction?
Sulphuric acid used in Lead Storage battery has a concentration of $$4.5 \mathrm{~M}$$ and a density of $$1.28 \mathrm{~g} / \mathrm{~ml}$$. The molality of the acid is __________.