What is the basic difference between the terms electron gain enthalpy and electronegativity?

Identify the incorrect set$(s)$ among the following periodic trends:

Explain the following:
$(a)$ Electronegativity of elements increases on moving from left to right in the periodic table.
$(b)$ Ionisation enthalpy decreases in a group from top to bottom.

Which of the following statement$(s)$ is/are incorrect?

Match the following elements,given as hints to their first,second ionization enthalpies and electron gain enthalpies.

List-$I$	List-$II$
$i)$ Most reactive non-metal	$A$. $\Delta H_1=419, \Delta H_2=3051, \Delta_{Eg} H=-48$
$ii)$ Most reactive metal	$B$. $\Delta H_1=1681, \Delta H_2=3374, \Delta_{Eg} H=-328$
$iii)$ Least reactive element	$C$. $\Delta H_1=738, \Delta H_2=1451, \Delta_{Eg} H=-40$
$iv)$ Metal forming binary halide	$D$. $\Delta H_1=3272, \Delta H_2=5251, \Delta_{Eg} H=+48$

Given below are two statements $:$
Statement $(I) :$ The radii of isoelectronic species increase in the order $Mg^{2+} < Na^{+} < F^{-} < O^{2-}$.
Statement $(II) :$ The magnitude of electron gain enthalpy of halogens decreases in the order $Cl > F > Br > I$.
In the light of the above statements,choose the most appropriate answer from the options given below $:$