(i) Copper metal dissolves in 1M silver nitrate solution and crystals of silver metal get deposited.
(ii) Siler metal does not react with 1M zinc nitrate solution.
Zinc metal dissolves in 1M copper sulphate solution and copper metal gets deposited
Hence the order of decreasing strength of the three metals as reducing agents will be

Options

A. `cugtAggtZn`
B. `Ag gt Cu gt Zn`
C. `Zn gt Cu gt Ag`
D. `Cu gt Zn gt Ag`

Answer

To determine the order of decreasing strength of copper (Cu), silver (Ag), and zinc (Zn) as reducing agents based on the given reactions, we can analyze the reactions and their corresponding standard reduction potentials (E°).

### Step-by-Step Solution:

1. **Understanding the Reactions:**
- **Copper in Silver Nitrate:**
- When copper metal is placed in 1M silver nitrate (AgNO₃), it dissolves and silver metal (Ag) is deposited. This indicates that copper is a stronger reducing agent than silver ions.
- Reaction:
\[ Cu(s) + 2Ag^+(aq) \rightarrow Cu^{2+}(aq) + 2Ag(s) \]

- **Silver in Zinc Nitrate:**
- Silver does not react with zinc nitrate (Zn(NO₃)₂), indicating that silver is not a strong enough reducing agent to reduce zinc ions.
- No reaction occurs here.

- **Zinc in Copper Sulfate:**
- Zinc metal dissolves in copper sulfate (CuSO₄) and copper metal is deposited. This indicates that zinc is a stronger reducing agent than copper.
- Reaction:
\[ Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s) \]

2. **Analyzing Standard Reduction Potentials (E°):**
- The standard reduction potentials for the half-reactions are as follows:
- \( Zn^{2+} + 2e^- \rightarrow Zn \) has \( E° = -0.76 \, V \)
- \( Cu^{2+} + 2e^- \rightarrow Cu \) has \( E° = +0.34 \, V \)
- \( Ag^+ + e^- \rightarrow Ag \) has \( E° = +0.80 \, V \)

3. **Determining Reducing Strength:**
- The more negative the standard reduction potential, the stronger the reducing agent. This is because a stronger reducing agent has a greater tendency to lose electrons (oxidize).
- Based on the E° values:
- Zinc (Zn) has the most negative potential (-0.76 V), making it the strongest reducing agent.
- Copper (Cu) has a potential of +0.34 V, making it weaker than zinc but stronger than silver.
- Silver (Ag) has the highest potential (+0.80 V), making it the weakest reducing agent.

4. **Order of Decreasing Strength:**
- Therefore, the order of decreasing strength of the three metals as reducing agents is:
\[ Zn > Cu > Ag \]

### Final Answer:
The order of decreasing strength of the three metals as reducing agents is:
\[ \text{Zinc (Zn) > Copper (Cu) > Silver (Ag)} \]