Write true or false for the statement: The term atomic size refers to the distance between the centre of the nucleus and the penultimate shell of an isolated atom.

Which of the following gives the correct increasing order of the atomic radii of $O$,$F$ and $N$?

Arrange the following metals in decreasing order of their atomic size: $Ca, Mg, Ba, Be$.

Arrange the following elements in the increasing order of their metallic character:
$Mg, Ca, K, Ge, Ga$

The elements $Be$,$Mg$,and $Ca$,each having two electrons in their outermost shells,are in periods $2$,$3$,and $4$ respectively of the modern periodic table. Answer the following questions,giving justification in each case:
$(i)$ Write the group to which these elements belong.
$(ii)$ Name the least reactive element.
$(iii)$ Name the element having the largest atomic radius.

What would be the nature of oxides formed by the elements on the right-hand side of the periodic table?