194?? One question

194?? One question (b) Th n1Y +3 oxidation state? (c) Pa 193. Which of the following lanthanoids ions is diamagnetic? (At. nos.•. Ce = 58, Sm = 62, 63, 70) (a) Sm2+ (b) Eu2+ (c) ce2+ 194. Which of the following orders of ionic radii is correctly represented? (d) A13+ > > NY 195. The species Ar, K + and Ca2+ contain the same number of electrons. In whi±z: radii increase? (c) Ar < < Cay

Dear student,  
Considering option (A), we have H+< H < H- . This is because H+ is just a proton, and H- has largest ionic radii due to high repulsion among 2 electrons.
In case of other options the elements are isoelectronic ( identical number of electrons), hence ionic radii increases with decrease in charge. Hence, 
Al3+ < Mg2+ < Na+ < F- < O2- < N3-

Hence none of the option is correct. There is some error in the options.

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Because an electon is added to flurene , 2 to oxygen and one is removed from sodium . All are done in the same shell , therefore c is correct
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Ans is a
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Answer is B
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(C) is correct .
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