`E^(@)` value of `Co^(2+), Co, Al^(3+) , Al , Ag^(+), Ag and Ba^(2+), Ba` are respectively `0.28, -1.66, +0.8 and -2.9 V`. write the increasing order of the reduction ability of metals and discuss .

Answer

To determine the increasing order of the reduction ability of the metals given their standard reduction potentials (E° values), we can follow these steps:

### Step 1: List the Standard Reduction Potentials
We start by listing the standard reduction potentials (E° values) for each metal ion and its corresponding metal:
- Co²⁺ / Co: E° = +0.28 V
- Al³⁺ / Al: E° = -1.66 V
- Ag⁺ / Ag: E° = +0.80 V
- Ba²⁺ / Ba: E° = -2.90 V

### Step 2: Understand the Concept of Reduction Potential
The standard reduction potential indicates how easily a species can gain electrons (be reduced). A higher (more positive) E° value means that the species is more likely to be reduced, while a lower (more negative) E° value indicates a stronger reducing agent (less likely to be reduced).

### Step 3: Arrange the E° Values in Ascending Order
To find the increasing order of reduction ability, we need to sort the E° values from lowest to highest:
1. Ba²⁺ / Ba: -2.90 V (most reducing)
2. Al³⁺ / Al: -1.66 V
3. Co²⁺ / Co: +0.28 V
4. Ag⁺ / Ag: +0.80 V (least reducing)

### Step 4: Write the Increasing Order of Reduction Ability
Based on the sorted E° values, we can write the increasing order of reduction ability of the metals:
- Ba < Al < Co < Ag

### Step 5: Discussion
From the order we derived, we can conclude that:
- Barium (Ba) is the strongest reducing agent among the metals listed, as it has the lowest E° value, indicating it is least likely to be reduced.
- Silver (Ag) is the weakest reducing agent, with the highest E° value, meaning it is most likely to be reduced.
- The trend shows that as the standard reduction potential increases, the ability of the metal to act as a reducing agent decreases.

### Summary
The increasing order of reduction ability of the metals is:
**Ba < Al < Co < Ag**