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 →

1. 2Fe + 3CuSO₄ →  Fe₂(SO₄)₃ + 3Cu.

2. Pb(NO₃)₂+ 2Kl →  PbI₂ + 2KNO₃.

3. Mg + 2HCl →  MgCl₂ + H₂.

4. H₂O →  H₂ + 1/2O₂.

5. 2Mg + O₂ → 2MgO.

Explanation:

1.Combine iron and copper (II) sulfate solution. (Hint: Iron will form the iron (III) ion)

2Fe + 3CuSO₄ →  Fe₂(SO₄)₃ + 3Cu.

It is a redox reaction including replacing Cu with Fe and changing their oxidation states.

That Fe replaces Cu and resulting in ferric sulfate.

2.Combine lead (II) nitrate and potassium iodide solutions.

Pb(NO₃)₂+ 2Kl →  PbI₂ + 2KNO₃.

It is a double replacement reaction that lead nitrate reacts with potassium iodide resulting in lead iodide and potassium nitrate.

3.Combine magnesium metal and hydrochloric acid solution.

Mg + 2HCl →  MgCl₂ + H₂.

It is a dissolution reaction that HCl dissolve Mg and resulting in Magnesium chloride and hydrogen gas is evolved.

4.Electrolysis (splitting) of water.  

H₂O →  H₂ + 1/2O₂.

Water electrolysis resulting in splitting of water to produce hydrogen and water.

5.Burning magnesium.

2Mg + O₂ → 2MgO.

It is a combustion reaction that Mg is burned with oxygen to produce magnesium oxide.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e