What are the differences between the first element of a group and the subsequent elements in the same group?

The isoelectronic set of ions is

Which of the following statements are correct?
$A.$ The process of the addition of an electron to a neutral gaseous atom is always exothermic.
$B.$ The process of removing an electron from an isolated gaseous atom is always endothermic.
$C.$ The $1^{st}$ ionization energy of boron is less than that of beryllium.
$D.$ The electronegativity of $C$ is $2.5$ in $CH_4$ and $CCl_4$.
$E.$ $Li$ is the most electropositive among elements of group $I$.
Choose the correct answer from the options given below:

Which of the following orders is not correct about the property shown against it?

Which of the following statements are correct?
$(i)$ First ionisation enthalpy of $He < $ Second ionisation enthalpy of $Li$.
$(ii)$ $Li$ has the highest second ionisation enthalpy.
$(iii)$ All $d$-block elements are transition elements.
$(iv)$ The only alphabet not found in the periodic table is the letter '$J$'.
$(v)$ Francium concentration is $\sim 10^{-18} \ ppm$ on Earth.

Select the correct order for the elements $B, C, N, O$: