Question

Among the second period elements the actual ionization enthalpies are in the orderLi

Answer 1

Explanation:

I) Be has elctrnic conf. 1s2 2s2 whereas B has E.C 1s2 2s2 2p1,as we can see that Be has its last orbital cmpltly filled therefore it is more stable than B ...Hence more energy will be required to remove n electron from Be than from B and it will have high ionisation enthlpy

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ii) EC of O is 1 s2 2s2 2p4...

EC of N is 1s2 2s2 2p3..

EC of F is 1s2 2s2 2p5

since O neither hs neither hlf filled nor fully filled orbital it is the least stable among these three ....therefore less energy will b required and hnce it will less I.E than O n F...