C. Flourine
Flourine is a pale yellow glass. It is the least dense and
the most active chemically. It displaces other halogens from their compounds
and also displaces oxygen from water. Bromine
is liquid with a dark red color. Chlorine is more dense and less reactive than fluorine.
It is a yellow-green gas. Iodine is a solid, grayish black in color and is the
least chemically active among the halogens. Among the nonmentals though, only
oxygen is more reactive than iodine.
