Question

Which statements among the following are correct?
I. $C{e}^{+4}$ is an oxidizing agent & colourless.
II. $L{u}^{3+}$ is colourless.
III. Actinoids exhibit a higher number of oxidation states than lanthanoids.
IV. All $3d$ elements give $H_2$ with $1MHCl$.

• A. II, III
• B. I, III
• C. I, II, III
• D. I, IV

Answer 1

Answer: (C)

I. $C{e}^{+4}$ formation favoured by its noble gas configuration, but it is a strong oxidant reverting to the common $+3$ state and it is colourless.
II. $L{u}^{3+}$ is diamagnetic and colourless.
III. Actinoids exhibit a higher number of oxidation states than lanthanoid due to lower energy difference between the consecutive 5 fand6 $d$ energy levels.
IV. All $3d$ elements do not give $H_2$ with $1MHCl$