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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3sb082

Take ionic radii (pm): $Li X^{+}$ 76, $Na X^{+}$ 102, $Mg X^{2 +}$ 72, $Be X^{2 +}$ 31, $Al X^{3 +}$ 54, and use charge/radius as the ionic potential. Which inferences are justified?

AThe ionic potential of Be2+ lies within 20 percent of that of Al3+
BThe ionic potential of Na+ is closer to that of Mg2+ than the ionic potential of Li+ is
CThe ionic potential of Li+ is closer to that of Mg2+ than to that of Be2+
DThe ionic potential of Mg2+ is more than three times that of Li+

Answer: A, C

In units of

1 0^{- 3} p m^{- 1}

: Li+ 13.2, Na+ 9.8, Mg2+ 27.8, Be2+ 64.5, Al3+ 55.6. Li-Mg differ by 14.6 and Li-Be by 51.3 (true); Be and Al differ by 8.9, which is 16 percent of Al (true). Na-Mg differ by 18.0, more than Li-Mg, and Mg/Li is 2.1, not above 3 (both false).

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