Which of the following statements is $NOT$ correct?

In general,the property (magnitudes only) that shows an opposite trend in comparison to other properties across a period 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?

The electronic configurations of $4$ atoms are given below:
$P = [Ne] \, 3s^2 3p^3$
$Q = [Ar] \, 3d^{10} 4s^2 4p^3$
$R = [He] \, 2s^2 2p^5$
$S = [Ne] \, 3s^1$
Which of the following statements is incorrect?

To which group and period does the element belong if the electronic configuration of an element in its $-2$ oxidation state is $1s^2 2s^2 2p^6 3s^2 3p^6$?