Arrange the following alkali metal ion in decreasing order of their mobility : `Li^(+), Na^(+), K^(+), Rb^(+), Cs^(+)`

Explanation

To arrange the alkali metal ions \(Li^+, Na^+, K^+, Rb^+, Cs^+\) in decreasing order of their mobility, we need to consider the factors that affect the mobility of ions in an aqueous solution.

### Step-by-Step Solution:

1. **Understanding Mobility**: Mobility refers to how quickly an ion can move through a solution. In aqueous solutions, smaller ions typically move faster than larger ions because they have less interaction with water molecules.

2. **Size of Ions**: The size of the alkali metal ions increases as we move down the group in the periodic table:
- \(Li^+\) (Lithium ion) is the smallest.
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