Which of the following statements is (are) incorrect?
(i) Percentage ionic character in `CsCl` bond is `~55%`. (Electronegativity values of Cs and Cl are 0.7 and 3.0 respectively)
(ii) From `H_(2)O` to `H_(3)O^(+)`, the geometry around O atom changes drastically .
(iii) The most stable oxidation state for element with atomic number 113 is expected to be `+2`.
(iv) The `2^("nd")` ionization energy of Ca is greater than `1^("st")` ionization energy of it but lower then `2^("nd")` ionization energyof K.

Options

A. Only i
B. i,ii, iii
C. ii, iii
D. iii, iv

Answer

To determine which statements are incorrect, we will analyze each statement one by one.

### Statement Analysis

1. **Statement (i)**: Percentage ionic character in CsCl bond is ~55%.
- **Electronegativity of Cs** = 0.7, **Electronegativity of Cl** = 3.0.
- The formula for percentage ionic character is:
\[ \text{Percentage Ionic Character} = 16 \times (x_A - x_B) + 3.5 \times (x_A - x_B)^2 \]
- Calculate the electronegativity difference:
\[ x_A - x_B = 3.0 - 0.7 = 2.3 \]
- Substitute into the formula:
\[ \text{Percentage Ionic Character} = 16 \times 2.3 + 3.5 \times (2.3)^2 \]
\[ = 36.8 + 3.5 \times 5.29 = 36.8 + 18.515 = 55.315\% \]
- This is approximately 55%, so **Statement (i) is correct**.

2. **Statement (ii)**: From H₂O to H₃O⁺, the geometry around the O atom changes drastically.
- H₂O has a bent shape due to two lone pairs on O (tetrahedral electron geometry, bent molecular geometry).
- H₃O⁺ has three bonding pairs and one lone pair, which also results in a tetrahedral electron geometry (but the molecular shape is trigonal pyramidal).
- The geometry does not change drastically; it remains tetrahedral. Therefore, **Statement (ii) is incorrect**.

3. **Statement (iii)**: The most stable oxidation state for element with atomic number 113 is expected to be +2.
- Element 113 (Nihonium, Nh) has the electron configuration: [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p¹.
- Due to the inert pair effect, the +1 oxidation state is more stable than +2. Thus, **Statement (iii) is incorrect**.

4. **Statement (iv)**: The 2nd ionization energy of Ca is greater than the 1st ionization energy of it but lower than the 2nd ionization energy of K.
- For Ca (atomic number 20), the first ionization energy (IE1) removes one electron from the 4s² configuration, while the second ionization energy (IE2) removes the second electron, resulting in a stable noble gas configuration.
- For K (atomic number 19), the first ionization energy removes one electron from 4s¹, and the second ionization energy removes an electron from a filled 3p⁶ configuration, which is more stable and thus has a higher IE.
- Therefore, **Statement (iv) is correct**.

### Conclusion
The incorrect statements are:
- **Statement (ii)**: Incorrect
- **Statement (iii)**: Incorrect

### Final Answer
The incorrect statements are (ii) and (iii).