Which of the following statement is incorrect?

Options

A. The tendency to attract bonded pair of electron in case of hybrid orbitals follow the order : `sp gt sp^(2) gt sp^(3)`
B. Alkali metals generally have negative value of electron gain enthalpy.
C. `Cs^(+)(g)` release more energy upon gain of an electron than `Cl(g)`.
D. The electronegativity values for `2p`-series elements is less than that for `3p`-series elements on account of small size and high inter electronic repulsions.

Explanation

To determine which of the statements is incorrect, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement 1:** The tendency to attract bonded pair of electrons in case of hybrid orbitals follows the order of sp > sp2 > sp3.

- **Explanation:** This statement is correct. The tendency to attract bonded pairs of electrons (which relates to electronegativity) is indeed influenced by the percentage of s-character in the hybrid orbitals. The more s-character, the greater the electronegativity.
- sp hybridization has 50% s-character.
- sp2 hybridization has approximately 33% s-character.
- sp3 hybridization has 25% s-character.

Thus, the order of electronegativity is sp > sp2 > sp3.

### Step 2: Analyze the second statement
**Statement 2:** Alkali metals generally have negative values of electron gain enthalpy.

- **Explanation:** This statement is also correct. Alkali metals (like sodium, potassium) tend to lose electrons rather than gain them. The electron gain enthalpy for alkali metals is typically negative, indicating that they do not favor gaining electrons.

### Step 3: Analyze the third statement
**Statement 3:** Cesium ion releases more energy upon gaining an electron than chlorine.

- **Explanation:** This statement is incorrect. The cesium ion (Cs⁺) has a stable noble gas configuration and does not have a strong tendency to gain an electron, thus it does not release significant energy upon gaining an electron. In contrast, chlorine (Cl) needs one electron to complete its octet and will release more energy when it gains an electron. Therefore, this statement is indeed incorrect.

### Step 4: Analyze the fourth statement
**Statement 4:** The electronegativity of 2P series elements is less than the 3P series elements on account of small size and higher inter-electronic repulsions.

- **Explanation:** This statement is incorrect. The electronegativity of 2P series elements is actually greater than that of 3P series elements. As we move down the group from 2P to 3P, the size of the atoms increases, and electronegativity decreases. Hence, this statement is also incorrect.

### Conclusion
The incorrect statements are:
- **Statement 3:** Cesium ion releases more energy upon gaining an electron than chlorine.
- **Statement 4:** The electronegativity of 2P series elements is less than the 3P series elements on account of small size and higher inter-electronic repulsions.

### Final Answer
The incorrect statements are C and D.

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