What tests would you use to identify a solution of fecl3

Your friend offers to show you an intrusive igneous rock. which of the following would you expect to see?

1. combine iron and copper (ii) sulfate solution. (hint: iron will form the iron (iii) ion) fe + cuso4 → 2. combine lead (ii) nitrate and potassium iodide solutions. pb(no3)2+ kl → 3. combine magnesium metal and hydrochloric acid solution. mg + hcl → 4. electrolysis (splitting) of water. h2o → 5. burning magnesium. mg + o2 →

What is the relation between concentration of reactants and the rate of chemical reaction?