The correct order of basic strength among the following is

Options

A. 1. `Li_(2)OltNa_(2)OltK_(2)OltRb_(2)O`
B. 2. `Rb_(2)OgtNa_(2)O=K_(2)OgtLi_(2)O`
C. 3. `Li_(2)OgtNa_(2)OgtK_(2)OgtRb_(2)O`
D. 4. `Na_(2)OgtLiO_(2)OgtK_(2)OgtRb_(2)O`

Explanation

To determine the correct order of basic strength among the given alkali metals (Lithium, Sodium, Potassium, Rubidium, Cesium), we can follow these steps:

### Step 1: Identify the Group
The elements in question belong to Group 1 of the periodic table, which includes Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), and Cesium (Cs).

### Step 2: Understand Basic Strength
Basic strength refers to the ability of an atom to donate an electron (or share an electron pair). In the context of alkali metals, this is related to their ability to form hydroxides (e.g., LiOH, NaOH, KOH, etc.) and the stability of the resulting cation.

### Step 3: Analyze Atomic Size
As we move down the group from Lithium to Cesium, the atomic size increases. This is due to the addition of electron shells.

### Step 4: Consider Effective Nuclear Charge
With the increase in atomic size, the effective nuclear charge experienced by the outermost electron decreases. This means that the outermost electron is held less tightly by the nucleus, making it easier to lose.

### Step 5: Compare Basic Strength
Since basic strength increases with the ease of losing the outermost electron, we can conclude that:
- Lithium (Li) has the weakest basic strength because it is the smallest and holds its outer electron more tightly.
- Sodium (Na) is stronger than Lithium.
- Potassium (K) is stronger than Sodium.
- Rubidium (Rb) is stronger than Potassium.
- Cesium (Cs) has the strongest basic strength because it is the largest and loses its outer electron most easily.

### Step 6: Write the Order
Thus, the correct order of basic strength is:
**Cs > Rb > K > Na > Li**

### Final Answer
The correct order of basic strength among the given alkali metals is:
**Cs > Rb > K > Na > Li**

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