Given`E^(c-)._(Ag^(o+)|Ag)=+0.80V,
E^(c-)._(Co^(2)|Co)=-0.28V, ``E^(c-)._ (Cu^(2+)|Cu)=+0.34V``
E^(c-)._(Zn^(2+)|Zn)=-0.76V`
Which metal will corrode fastest ?

Options

A. `Ag`
B. `Cu`
C. `Co`
D. `Zn`

Explanation

To determine which metal will corrode the fastest among the given options, we will analyze the standard reduction potentials provided for each metal. The lower the reduction potential, the more likely the metal is to oxidize (corrode).

### Step-by-Step Solution:

1. **List the Reduction Potentials:**
- \( E^\circ (Ag^+|Ag) = +0.80 \, V \)
- \( E^\circ (Co^{2+}|Co) = -0.28 \, V \)
- \( E^\circ (Cu^{2+}|Cu) = +0.34 \, V \)
- \( E^\circ (Zn^{2+}|Zn) = -0.76 \, V \)

2. **Identify the Lowest Reduction Potential:**
- Among the listed potentials, we compare the values:
- Silver (Ag): +0.80 V
- Cobalt (Co): -0.28 V
- Copper (Cu): +0.34 V
- Zinc (Zn): -0.76 V
- The lowest value is for Zinc, which is -0.76 V.

3. **Determine the Corrosion Tendency:**
- Metals with lower reduction potentials are more likely to oxidize. Therefore, they corrode faster.
- Since Zinc has the lowest reduction potential (-0.76 V), it is the most susceptible to corrosion.

4. **Conclusion:**
- Based on the analysis, Zinc will corrode the fastest among the given metals.

### Final Answer:
Zinc will corrode the fastest.