Deterioration of buildings, bridges, and other structures

Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars every day. Although the actual process also requires water, a simplified equation (with rust shown as Fe2O3) is 4Fe(s)+3O2(s)→2Fe2O3(s)ΔHrxn=?1.65×103kJ

a) How much heat is evolved when 0.250 kg of iron rusts?
b) How much rust forms when 4.85×103kJ4.85×103kJ of heat is released?