Maximum enthalpy change is associated with which of the following reactions?

The ground state electronic configurations of the elements,$U, V, W, X,$ and $Y$ (these symbols do not have any chemical significance) are as follows:
$U: 1s^2 2s^2 2p^3$
$V: 1s^2 2s^2 2p^6 3s^1$
$W: 1s^2 2s^2 2p^6 3s^2 3p^2$
$X: 1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 4s^2$
$Y: 1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6$
Determine which sequence of elements satisfies the following statements:
$(i)$ Element forms a carbonate which is not decomposed by heating
$(ii)$ Element is most likely to form coloured ionic compounds
$(iii)$ Element has the largest atomic radius
$(iv)$ Element forms only acidic oxide

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:

The first element of a group differs in many ways from the other heavier members of the group due to:

The element with a very high ionization enthalpy but zero electron gain enthalpy is ....

Which of the following orders is $NOT$ correct with respect to the mentioned properties?