Study the variation in the atomic radii of Group $I$ elements given below and arrange them in an increasing order.
$(i)$ Name the elements which have the smallest and the largest atoms.

Group $I$ elements

$Li: 52\, pm, Na: 61\, pm, K: 231\, pm, Rb: 244\, pm, Cs: 262\, pm$

$(ii)$ How does the atomic size vary as you go down a group?

The order of decreasing atomic size is:

The position of three elements $A$, $B$, and $C$ in the Periodic Table are shown below:

Group $16$	Group $17$
-	-
-	$A$
-	-
$B$	$C$

$(a)$ State whether $A$ is a metal or non-metal.
$(b)$ State whether $C$ is more reactive or less reactive than $A$.

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

The atomic numbers of three elements $A, B$,and $C$ are $12, 18$,and $20$ respectively. State,giving reason,which two elements will show similar properties.

The atomic radii of the elements of the second period are given below:

Second period elements	$B$	$Be$	$O$	$N$	$Li$	$F$	$C$
Atomic Radii $(pm)$	$88$	$111$	$66$	$74$	$152$	$64$	$77$

$(i)$ Arrange these elements in decreasing order of their atomic radii.
$(ii)$ Are the elements now arranged in the pattern of a period in the periodic table?
$(iii)$ Name the element which has the $(a)$ smallest and $(b)$ largest atomic number.
$(iv)$ From the above data, infer how the atomic size or atomic radius of the elements changes as we move from left to right in a period.
$(v)$ Name one metal, one non-metal, and a metalloid out of these elements.
$(vi)$ Why does atomic radius decrease as we move from left to right in a period?