Which material would be totally involatile?
#"iii. ammonium chloride;"#
Graphite is the only material that is NON-MOLECULAR; camphor, and iodine are molecular. Ammonium chloride is a salt, that could be decomposed with heating to give
On the other hand, graphite is composed of an infinite array of carbon-carbon bonds in two dimensions, and as a result has highly elevated melting and boiling points. Graphite is thus non-volatile, and non-sublimable.