Given below are two statements:
Statement-$I$: The correct order in terms of atomic/ionic radii is $Al > Mg > Mg^{2+} > Al^{3+}$.
Statement-$II$: The correct order in terms of the magnitude of electron gain enthalpy is $Cl > Br > S > O$.
In the light of the above statements, choose the correct answer from the options given below:

The isoelectronic set of ions is

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

Which of the following statements are not correct?
$A.$ The electron gain enthalpy of $F$ is more negative than that of $Cl$.
$B.$ Ionization enthalpy decreases in a group of the periodic table.
$C.$ The electronegativity of an atom depends upon the atoms bonded to it.
$D.$ $Al_2O_3$ and $NO$ are examples of amphoteric oxides.
Choose the most appropriate answer from the options given below:

$A, B$,and $C$ are hydroxy-compounds of the elements $X, Y$,and $Z$ respectively. $X, Y$,and $Z$ are in the same period of the periodic table. $A$ gives an aqueous solution of $pH < 7$. $B$ reacts with both strong acids and strong alkalis. $C$ gives an aqueous solution which is strongly alkaline.
Which of the following statements is / are true?
$I$: The three elements are metals.
$II$: The electronegativities decrease from $X$ to $Y$ to $Z$.
$III$: The atomic radius decreases in the order $X, Y$,and $Z$.
$IV$: $X, Y$,and $Z$ could be phosphorus,aluminium,and sodium respectively.

Consider the following:
$(I)$ The order of first ionisation enthalpy of the first three elements of the $3^{rd}$ period is $Mg > Al > Na$
$(II)$ The element with an electronegativity of $3.5$ is chlorine
$(III)$ The order of sizes of ions $Mg^{2+}, Na^{+}, F^{-}$ and $O^{2-}$ is $Mg^{2+} < Na^{+} < F^{-} < O^{2-}$
$(IV)$ The $IUPAC$ name of the element with atomic number $106$ is Bohrium.
The correct statements are