A) \[S{{m}^{+2}},E{{u}^{2+}}\] and \[Y{{b}^{2+}}\] ions in solution are good oxidising agents but an aqueous solution of \[C{{e}^{4+}}\] is a good reducing agent.
B) \[M{{n}^{+2}}\]shows maximum paramagnetic character amongst the \[+2\] ions of \[{{I}^{st}}\] transition series.
C) \[La{{(OH)}_{3}}\] is more basic than \[Lu{{(OH)}_{3}}\]
D) \[F{{e}^{2+}},M{{n}^{2+}}\] and \[C{{r}^{3+}}\] ions are coloured.
Correct Answer: A
Solution :
[a] Statement (1) is INCORRECT CORRECT statement: Reverse statement is CORRECT The most stable oxidation state of lanthanides is \[+3\]hence ions in \[+2\] state tend to change to\[+3\] state by loss of electron and those in +4 state tend to change to \[+3\] state by gain of electron. (2) \[M{{n}^{2+}}\] has maximum number of unpaired electrons. As the size of lanthanide ions decreases from \[L{{a}^{3+}}\]to \[L{{u}^{3+}},\] the coyalent character of the hydroxides increases. Hence the basic strength decreases from \[La{{(OH)}_{3}}\]to \[Lu{{(OH)}_{3}}\]. (4) \[F{{e}^{2+}},M{{n}^{2+}},C{{r}^{3+}}\]are coloured due to d-d transition of electron takes place.
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