Copper from copper sulphate solution can be displacesd by. (The standard reduction potentials of some electrodes are given below):
`E^(o)(Fe^(2+)//Fe) = - 0.44 V, E^(o) (Zn^(2+)//Zn) = - 0.76 V`
`E^(o) (Cu^(2+)//Cu) = + 0.34 V: E^(o)(Cr^(3+)//Cr) = - 0.74 V`
`E^(o) (H^(+)// 1/2H_(2)) = 0.00V`

Options

A. `H_(2)`
B. Zn
C. Cr
D. All of these

Answer

To determine which species can displace copper from a copper sulfate solution, we need to analyze the standard reduction potentials provided for various electrodes. The relevant standard reduction potentials are:

- \( E^{\circ}(Cu^{2+}/Cu) = +0.34 \, V \)
- \( E^{\circ}(Fe^{2+}/Fe) = -0.44 \, V \)
- \( E^{\circ}(Zn^{2+}/Zn) = -0.76 \, V \)
- \( E^{\circ}(Cr^{3+}/Cr) = -0.74 \, V \)
- \( E^{\circ}(H^+/H_2) = 0.00 \, V \)

### Step-by-Step Solution:

1. **Understanding Displacement Reaction**:
A metal can displace another metal from its salt solution if it has a higher oxidation potential (or lower reduction potential). In this case, we want to see if any of the given metals can displace copper from copper sulfate.

2. **Identify the Reduction Potential of Copper**:
The standard reduction potential for copper is \( +0.34 \, V \). This means that copper ions (\( Cu^{2+} \)) can easily be reduced to copper metal.

3. **Compare Other Metals' Reduction Potentials**:
We will compare the reduction potentials of the other metals with that of copper:
- **Iron**: \( E^{\circ}(Fe^{2+}/Fe) = -0.44 \, V \) (lower than copper)
- **Zinc**: \( E^{\circ}(Zn^{2+}/Zn) = -0.76 \, V \) (lower than copper)
- **Chromium**: \( E^{\circ}(Cr^{3+}/Cr) = -0.74 \, V \) (lower than copper)
- **Hydrogen**: \( E^{\circ}(H^+/H_2) = 0.00 \, V \) (lower than copper)

4. **Conclusion**:
All the given metals (Fe, Zn, Cr, and H) have lower reduction potentials than copper. Therefore, they can all displace copper from copper sulfate solution.

5. **Final Answer**:
The correct answer is that copper can be displaced by all of these species. Thus, the answer is option 4: "All of these".