Question

If the ionisation potential of $Na$ is $5.48eV$, the ionisation potential of $K$ will be

• A. Same as that of $Na$
• B. $4.4eV$
• C. $5.68eV$
• D. $10.88eV$

Answer 1

The correct option is B $4.4eV$

Down the group in periodic table, the size of element increases due to increase in number of shells.
So, energy required to remove an electron from $K$ is lesser than $Na$.
Thus, the value of ionisation potential of $K$ is less than $Na$.
Hence, option (b) is the correct answer.