Question

Second ionisation potential of $Li,Be,B$ is in the order:

• A. $Li>Be>B$
• B. $Li>B>Be$
• C. $Be>Li>B$
• D. $B>Be>Li$

Answer 1

Answer: (B)

$Li>B>Be$

Second ionization potential will be greatest because in $L{i}^{+}$ $\left(He\right)$ we have to remove an electron from a lithium ion equivalent to helium atom. Which is known for its high ionization energy values.

In $B{e}^{1+}$ electronic configuration is $1s^{2}2s^1$

Whereas Boron ($B^{+}$) is 1s${}^{2}2s^2$

We know it is difficult to remove a stable paired electron than compared to a single unpaired electron in a same orbital.

So, $Li>B>Be$ is the order.