The Pair Of Elements Having Approximately Equal Ionisation Potential Is

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The pair of elements having approximately equal ionisation potential is


Correct option is

Al, Ga


Ionisation energy increases with decreases in atomic size and decrease in shielding effect.  

Al(13) = 1s2, 2s2, 2p6, 3s2, 3p1   

Ga(31) = 1s2, 2s2, 2p6, 3s2, 3p6, 4d10, 4s2, 4p1  

As the atomic electronic configuration show there are ten d-electrons in Ga which shield the nuclear charge less effectively than s and p electrons. Hence, the outer electron is held fairly strongly by the nucleus. Consequently ionisation energy slightly increases inspite of the increase in atomic size from Al to Ga. Hence, Al and Ga have approximately equal ionisation potential.   



Which of the following transition involves maximum amount of energy?



The formation of the oxide ion O2–(g) requires first an exothermic and then an endothermic step as shown below  



This is because 


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The least stable ion among the following is


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The set representing the correct order of ionic radius is


Which is not the correct order for the stated property?