Question

Which of the following pairs has the highest difference in their first ionization energy?

• A. $Xe,Cs$
• B. $Kr,Rb$
• C. $Ar,K$
• D. $Ne,Na$

Answer 1

Answer: (D)

I.E. increases from left to right and decreases from top to bottom in the periodic table. $Ne$ (noble gas) and $Na$ (alkali metal) belong to $2^{nd}$ and $3^{rd}$ period respectively and show highest difference in their first I.E., subsequent members of the same group show lower I.E. on moving down in the group