Consider the following statements
1. `Cs^+` ion is more highly hydrated than other alkali metal ions
2. Among the alkali metals Li, Na , K and Rb, Lithium (Li) has the highest melting point
3. Among the alkali metals , only lithium form a stable nitride by direct combination .
O these statements

Options

A. 1,2 and 3 are correct
B. 1 and 2 are correct
C. 1 and 3 are correct
D. 2 and 3 correct

Answer

To solve the question, we need to evaluate each of the three statements regarding alkali metal ions and determine their correctness.

### Step 1: Evaluate Statement 1
**Statement 1:** `Cs^+` ion is more highly hydrated than other alkali metal ions.

- **Analysis:** Hydration energy depends on the size of the ion and its charge. As we move down the group in the periodic table, the size of the alkali metal ions increases (Li < Na < K < Rb < Cs). Larger ions have lower charge density, which leads to lower hydration energy. Therefore, `Li^+` will have the highest hydration energy because it is the smallest ion among the alkali metals. Thus, `Cs^+` is not more highly hydrated than other alkali metal ions.
- **Conclusion:** **Statement 1 is incorrect.**

### Step 2: Evaluate Statement 2
**Statement 2:** Among the alkali metals Li, Na, K, and Rb, Lithium (Li) has the highest melting point.

- **Analysis:** The melting point of alkali metals is influenced by lattice energy and ionization enthalpy. Smaller ions have higher ionization energies and stronger lattice energies, leading to higher melting points. Lithium, being the smallest alkali metal, has the highest melting point among them.
- **Conclusion:** **Statement 2 is correct.**

### Step 3: Evaluate Statement 3
**Statement 3:** Among the alkali metals, only lithium forms a stable nitride by direct combination.

- **Analysis:** Lithium reacts with nitrogen to form lithium nitride (Li3N), which is stable due to high lattice energy. Other alkali metals do not form stable nitrides under normal conditions. Therefore, this statement is true.
- **Conclusion:** **Statement 3 is correct.**

### Final Conclusion
- **Correct Statements:** Statement 2 and Statement 3 are correct.
- **Incorrect Statement:** Statement 1 is incorrect.

### Answer
The correct option is **Option 4: 2 and 3 are correct.**

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