Let's go through the three reactions in the image and identify if they are redox reactions, along with the reducing and oxidizing agents for each.

1. Reaction:

$3Cr(NO_3)_2(aq) + 2Al(s) \rightarrow 3Cr(s) + 2Al(NO_3)_3(aq)$

• Redox reaction?: Yes
• Explanation: In this reaction, chromium (Cr) is reduced from $Cr^{2+}$ in the nitrate solution to Cr(s), while aluminum (Al) is oxidized from Al(s) to $Al^{3+}$ in the nitrate compound.
  • Reducing agent: Aluminum (Al), since it loses electrons (is oxidized).
  • Oxidizing agent: Chromium ion $Cr^{2+}$, since it gains electrons (is reduced).

2. Reaction:

$2Na(s) + Cl_2(g) \rightarrow 2NaCl(s)$

• Redox reaction?: Yes
• Explanation: Sodium (Na) is oxidized from Na(s) to $Na^+$, and chlorine (Cl) is reduced from $Cl_2$ to $Cl^-$ in sodium chloride (NaCl).
  • Reducing agent: Sodium (Na), as it is oxidized (loses electrons).
  • Oxidizing agent: Chlorine gas ($Cl_2$), as it is reduced (gains electrons).

3. Reaction:

$2N_2(g) + 5O_2(g) \rightarrow 2N_2O_5(g)$

• Redox reaction?: No
• Explanation: In this reaction, nitrogen and oxygen are simply combining to form dinitrogen pentoxide without a change in their oxidation states. This is a synthesis reaction but not a redox reaction.

Would you like more detailed explanations or have any other questions?

Here are 5 related questions you might find interesting:

1. What are the rules for identifying oxidation and reduction in chemical reactions?
2. How do oxidation states help determine if a reaction is redox?
3. Can a reaction have both a reducing and oxidizing agent that are the same substance?
4. What is the significance of balancing redox reactions in electrochemistry?
5. How does the environment (acidic vs basic) affect redox reactions?

Tip: In a redox reaction, the substance that loses electrons is always the reducing agent, and the substance that gains electrons is the oxidizing agent.