Among the following,the least and most metallic elements will be respectively:
$(I) [He] 2s^1$
$(II) [Kr] 5s^2 4d^{10} 5p^5$
$(III) [Xe] 6s^1$
$(IV) [He] 2s^2 2p^5$

Consider the following four elements,which are represented according to the long form of the periodic table. Here $W$,$Y$,and $Z$ are left,up,and right elements with respect to the element $X$,and $X$ belongs to the $16^{th}$ group and $3^{rd}$ period. Then,according to the given information,the incorrect statement regarding the given elements is:

$Fe x_2$ and $Fe y_3$ are known when $x$ and $y$ are :

The correct order of acid strength is

Which of the following is the correct order of acidic strength?

Which one of the following orders correctly represents the increasing acid strengths of the given acids?