The stability of +1 oxidation state in aqueous solution is in the order-
A l < G a > I n > T l
T l > In > G a > A l
A l > T l > G a > In
T l > A l > G a > In

Options

A. `Al lt Ga gt "In gt Tl`
B. `Tl gt "In" gt Ga gt Al`
C. `Al gt Tl gt Ga gt "In"`
D. `Tl gt Al gt Ga gt "In"`

Explanation

To determine the stability of the +1 oxidation state in aqueous solution for the elements Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl), we can analyze the factors affecting their oxidation states, particularly focusing on the inert pair effect.

### Step-by-Step Solution:

1. **Understanding the Elements**:
- The elements in question are Al, Ga, In, and Tl. They belong to group 13 of the periodic table.

2. **Identifying Oxidation States**:
- These elements can exhibit +1 and +3 oxidation states. However, the stability of the +1 oxidation state varies among them.

3. **Inert Pair Effect**:
- The inert pair effect refers to the tendency of the outermost s-electrons (the 'inert pair') to remain unbonded or unshared in heavier elements. This effect becomes more pronounced as we move down the group in the periodic table.

4. **Analyzing Each Element**:
- **Aluminium (Al)**: Has a +3 oxidation state that is more stable due to the inert pair effect. Thus, it has the least stability for the +1 state.
- **Gallium (Ga)**: Also has a +3 oxidation state, but the +1 state is slightly more stable than Al.
- **Indium (In)**: The +1 oxidation state becomes more stable compared to Ga due to the increased inert pair effect.
- **Thallium (Tl)**: Exhibits the strongest +1 oxidation state stability among these elements due to the significant inert pair effect.

5. **Ordering the Stability**:
- Based on the analysis, the order of stability for the +1 oxidation state in aqueous solution is:
- **Tl > In > Ga > Al**

6. **Conclusion**:
- Therefore, the correct answer is that the stability of the +1 oxidation state in aqueous solution is in the order: **Tl > In > Ga > Al**.