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:

In which of the following arrangements,the sequence does not strictly follow the property indicated against it?

An element $E$ has an ionisation enthalpy value of $374 \ kJ \ mol^{-1}$. $E$ reacts with elements $A, B, C$ and $D$ with electron gain enthalpy values of $-328, -349, -325$ and $-295 \ kJ \ mol^{-1}$,respectively. The correct order of the products $EA, EB, EC$ and $ED$ in terms of ionic character is $:$

Identify the incorrect statement.

Outermost electronic configuration of a group $13$ element,$E$,is $4s^2 4p^1$. The electronic configuration of an element of $p$-block,period $5$,placed diagonally to element $E$ is: