form four chem. 20分. plz.

if u are alreayd using steam or hot water, the heating part is not necessary, and i dont understand what do u mean by 'heating wet sand/mg'. im not sure if there will be light, but im positive. it will be essentially the same as if u react mg metal with hot water instead of steam.

yes, fe2+ cation will turn to fe metal when reacting with a reducing agent and itself simotaneously act as a oxidizing agent and help through the other reactant to go through oxidization.

for I, it should be I2. and yes, I2 solid will become I- anion when reduced and I2 will be synthesised when oxidixed.

im not sure if sulfuric acid must not react in a diluted form. however, due to one of the fundamental principles of thermodynamics, excess reactant can force the reaction go to the the product side. that means if u have excess reducing agent, u will make the the diluted sulfuric acid to go through reduction (SO4 2- >>> SO2) as well. but ultimately, it really all depends how diluted is your sulfuric acid. usually, diluted sulfuric acid is used as a catalysis, if u truely want a redox reaction to go, u would want to use a sufficient amount of acid.

for instance, sulfuric acid will react with copper (II) oxide to give u copper (II) sulfate in water. it can also react with metal iron to give u iron sulfate and hydrogen gas.