In which one of the following pairs will the first system have a higher entropy than the second?

Assume $P$ and $T$ are the same for each pair, unless stated otherwise.

$1$ mole $He(g)$; $1$ mole $Kr(g)$

$1$ mole $xe(g)$ at $1$ atmosphere; $1$ mole $xe(g)$ at $0\mathrm{.}5$ atmosphere

$1$ mole $C{H}_4(g)$; $1$ mole $C_2{H}_6($g$)$

$1$ mole $O_2(g)$;$2$ mole $O(g)$

$2$ mole $O(g)$;$1$ mole $O_2(g)$