A neutralization reaction is the reaction between an acid and a base to produce water and a salt. A salt is another name for an ionic compound and the specific salt produced depends on the acid and base involved. The product solution is neutral while the starting solutions are acidic and basic respectively.
They are composed of rock, dust, ice and frozen gases such as carbon monoxide, carbon dioxide, methane, and ammonia. Sometimes called dirty snowballs, recent studies have shown that the ice of a comet is covered by a crust. Comets also contain a variety of organic compounds as well as the gases already mentioned.