Which of the following statements is incorrect?

Fill in the blanks given below:
$(i)$ The most widely used scale for measuring electronegativity is ........ .
$(ii)$ The similarity observed in periodic properties is known as .............. .
$(iii)$ The elements located in the middle of the periodic table form .......... type of oxides.

Which of the following statements is incorrect?

$A, B$,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.

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:

If the period number and group number of any representative element are the same,then which of the following statements is incorrect regarding such type of element in its ground state? (Period number and group number are according to the modern form of the periodic table)