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

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.

Observe the following statements:
$I$. The physical and chemical properties of elements are periodic functions of their electronic configuration.
$II$. Electronegativity of fluorine is less than the electronegativity of chlorine.
$III$. Electropositive nature decreases from top to bottom in a group.
The correct answer is:

Identify the correct statements from the following.
$(i)$ In the periodic table,about $78 \%$ of elements are metals.
$(ii)$ In a group,the metallic character decreases from top to bottom and in a period the nonmetallic character decreases from left to right.
$(iii)$ The element $Ho$ belongs to $f-$block.

Match the following and select the correct option:

List-$I$	List-$II$
$(A)$ Ionization enthalpy	$(i)$ $P < Si < Mg < Na$
$(B)$ Metallic character	$(ii)$ $I < N < O < F$
$(C)$ Electron gain enthalpy	$(iii)$ $B < Be < C < O < N$
$(D)$ Electronegativity	$(iv)$ $I < Br < F < Cl$