Heat lost = mcΔT, where m is the mass of iron , c is the specific heat capacity of iron, and ΔT is the change in temperature.
Mass of iron = 350 g, specific heat capacity = 0.450 J/gC while;
change in temperature = 54.1 - 22.4 = 31.7
Hence; heat = 350 × 0.450 × 31.7
= 4992.75 J or 4.993 kJ