13. How many chemical reactions from the given reactions are exothermic reactions?<table class='rte_tbl' width='493' height='26' cellspacing='0' cellpadding='0' border='1' align=''><tbody><tr><td width='100%%'> Melting of Ice cube, mixing of salt and water condensation of vapour into water, cooking of egg, rusting of iron, acid-base reaction (neutralisation)</td></tr></tbody></table> *