Question

The incorrect statement among the following is
(a) The first ionization potential of Al is less than the first ionization potential of Mg
(b) The second ionization potential of Mg is greater than the second ionization potential of Na
(c) The first ionization potential of Na is less than the first ionization potential of Mg
(d) The third ionization potential of Mg is greater than the third ionization potential of Al.

Answer 1

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The second ionization potential of Mg is greater than the second ionization potential of Na

Answer 2

Explanation:

Ionization potential or energy (IE) increases across a period but with certain breaks. IE1 of Al(3s1p1) is less than IE1 of Mg(3s2) as electron is to be removed from 3p which is easy as compared to 3s. Further IE3 shows the reverse trend because now for Al2+(3s1) electon is to be removed from 3s as compared to the completely filled 2p orbitals in Mg2+. The same becomes true for IE2 of Na, hence option (b) is correct.