Question

According to the location in periodic table which statement(s) regarding the first ionization energies of specific elements should be true?
I. $Li$ has a higher value than $Na.$
II. $K$ has a higher value than $Cs.$
III. $Na$ has a higher value than $Al$

• A. I only
• B. III only
• C. I and II only
• D. II and III only
• E. I, II and III

Answer 1

Answer: (C)

I and II only

1.In moving down the group as the size increases the ionization energy decreases.So $Li$ has a higher value than $Na$, and $K$ has a higher value than $Cs$ of group $I$
2.In moving across a period as the atomic size decreases due to an addition of electron in the same shell the ionization energy increases.So $Na$ has the lower value than the $Al$ in period $3.$