In Endothermic reactions, energy is absorbed.
Ranking of the ions in each set in order of decreasing size -
Cs+ > Ba²⁺ > Sr²⁺
Cs+ has the biggest size, because its more downward (compared to Sr2+) and more to the left (compared) ot Ba2+.
Sr2+ has the smallest size because it's more upwords (compared to Cs+ and Ba2+).
For isoelectronic ions, the greater the nuclear charge , the greater is the attraction for electrons and smaller is ionic radius. In other words, size of the isoelectronic ions decreases with increase in atomic number.
Cl3+ has the smallest ion among all.
To learn more about ions from given link
brainly.com/question/14658491
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Option B is the correct answer
