4. indicate the ionic equation, the net-ionic equation, and the spectator ions of the following
molecular equation.
hcl(aq)
+
fe2o3(s)
→
fecl3(aq)
+
h2o(1)

Explanation:

Chemical equation:

HCl + Fe₂O₃  → FeCl₃ + H₂O

Balanced Chemical equation:

6HCl (aq)+ Fe₂O₃(s)  → 2FeCl₃(aq) + 3H₂O(l)

Ionic equation:

6H⁺(aq) + 6Cl⁻(aq) + 2Fe⁺³(aq) + 3O²⁻(aq) → 2Fe⁺³(aq) + 6Cl⁻(aq) + 3H₂O(l)

Net ionic equation:

6H⁺(aq) + 3O²⁻(aq) →  3H₂O(l)

The Cl⁻(aq) and Fe⁺³(aq) are spectator ions that's why these are not written in net ionic equation. The water can not be splitted into ions because it is present in liquid form.

Spectator ions:

These ions are same in both side of chemical reaction. These ions are cancel out. Their presence can not effect the equilibrium of reaction that's why these ions are omitted in net ionic equation.  

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

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.