The reaction is a displacement reaction. Iron is more reactive than copper. Hence, it displaces copper,forming iron II sulfate and copper metal.
This reaction is an exothermic reaction, hence it releases energy. The colour change indicates that iron has displaced copper.
Answer= 2 mol/dm^3
Explanation:-
Firstly, we convert the volume, which is in cm^3 to dm^3. To do that divide number in cm^3 by 1000:
100/1000= 0.1 dm^3
Formula for concentration is:
Concentration= No. of moles/ Volume
So,
Concentration= 0.2/0.1
Answer= 2 mol/dm^3
I divided the volume by a 1000 because it must be in litres, but it wont make any difference because they will cancel out, but you must always convert it to L or dm3 unless it says in the question something else.