Explain the following:
“The first ionisation energy of carbon atom is greater than that of boron atom whereas, the reverse is true for the second ionisation energy.

Explanation

`C_(6)-1s^(2) 2s^(2) 2p^(2), B_(5)-1s^(2) 2s^(2) 2p^(1)`
In first case, `IE_1" of "C gt IE_1` of B. Since carbon is smaller than B in size. But `IE_2 (B) gt IE_2 (C)` because electrons are paired as well as present in inner s-orbital whereas for carbon, electrons will be still in 2p orbital and in unpaired state.