Which of the following has the lowest first ionisation potential?

The first ionisation energy of lithium $(Li)$ will be

If energy absorbed for conversion of $M_{(g)}$ into $M_{(g)}^{+}$ for $Li, Be, B, C$ and $N$ is $a, b, c, d$ and $e$ (in $k\,cal/mol$) respectively,then the correct order will be:

The ionization energy of hydrogen is:

Ionisation energy in group $I$ elements varies in the decreasing order as:

Generally,the first ionisation energy increases along a period. But there are some exceptions. The one which is not an exception is