In a period, the first ionisation enthalpy of the element at the extreme left and the negative electron gain enthalpy of the extreme right element, except noble gases, are respectively.

The change in enthalpy $[\Delta H]$ in $kJ\ mol^{-1}$ for the reaction is $Mg + 2F \rightarrow MgF_2$. Given: $EA$ of $F = 328\ kJ\ mol^{-1}$, $IE_1$ of $Mg = 737\ kJ\ mol^{-1}$, $IE_2$ of $Mg = 1451\ kJ\ mol^{-1}$.

In general,the properties that decrease and increase down a group in the periodic table respectively are

Which one among the following statements is/are not correct?
$I$. $Ba$ compounds,generally are more covalent than $Be$ compounds.
$II$. The electron gain enthalpy of $He$ is positive.
$III$. The oxidation state of $O$ in $OF_2$ and $Na_2O$ are same.
$IV$. The radius of $Na^{+}$ ion is smaller than that of $F^{-}$ ion.

Which of the following statements is correct regarding the following processes?
$(i) \, Cl$ $\xrightarrow{E.A.} Cl^{-} \, \, \, \, \, (ii) \, Cl^{-}$ $\xrightarrow{I.E.} Cl \, \, \, (iii) \, \, Cl$ $\xrightarrow{I.E.} Cl^{+} \, \, \, (iv) \, \, Cl^{+}$ $\xrightarrow{I.E.} Cl^{2+}$

Which one of the following is an incorrect statement?