Which of the following statements are correct?

Options

A. The electron affinity of Si is greater than that of C.
B. BeO is amphoteric while `B_2 O_3` is acidic.
C. The ionization energy of Ti is less than that of Al.
D. The ionization energy of elements of Cu-group is less than that of the respective elements of Zn-group.

Answer

To determine which statements are correct regarding the properties of elements, we will analyze each statement step by step.

### Step 1: Analyze the first statement
**Statement:** The electron affinity of silicon is greater than that of carbon.

**Explanation:**
- **Definition:** Electron affinity is the energy released when an electron is added to an atom.
- **Comparison:** Carbon (C) is smaller in size compared to silicon (Si) because it is higher up in the group in the periodic table.
- **Reasoning:** A smaller atomic size in carbon leads to greater electron-electron repulsion when an electron is added. In contrast, silicon, being larger, experiences less repulsion. Therefore, the electron affinity of silicon is indeed greater than that of carbon.

**Conclusion:** This statement is correct.

### Step 2: Analyze the second statement
**Statement:** Beryllium oxide is amphoteric while B2O3 is acidic.

**Explanation:**
- **Beryllium Oxide (BeO):** It has amphoteric properties, meaning it can react with both acids and bases.
- **Boron Trioxide (B2O3):** The oxidation state of boron in B2O3 is +3. Boron oxides typically exhibit acidic behavior because they can accept electrons.

**Conclusion:** This statement is correct.

### Step 3: Analyze the third statement
**Statement:** The ionization energy of titanium is less than that of aluminum.

**Explanation:**
- **Electron Configuration:** Titanium (Ti) has an electron configuration of [Ar] 3d² 4s², while aluminum (Al) has [Ne] 3s² 3p¹.
- **Reasoning:** Aluminum can easily lose its outermost electron to achieve a stable configuration. Titanium has a more complex electron configuration with d-electrons that experience less shielding, leading to a stronger attraction to the nucleus. Thus, titanium has a higher ionization energy than aluminum.

**Conclusion:** This statement is incorrect.

### Step 4: Analyze the fourth statement
**Statement:** The ionization energy of the copper group is less than that of the respective zinc group.

**Explanation:**
- **Electron Configuration:** Copper (Cu) has an electron configuration of [Ar] 3d¹⁰ 4s¹, while zinc (Zn) has [Ar] 3d¹⁰ 4s².
- **Reasoning:** Zinc has a stable electron configuration (completely filled d-subshell), making it harder to remove an electron compared to copper. Therefore, the ionization energy of zinc is higher than that of copper.

**Conclusion:** This statement is correct.

### Final Summary
The correct statements are:
1. The electron affinity of silicon is greater than that of carbon.
2. Beryllium oxide is amphoteric while B2O3 is acidic.
4. The ionization energy of copper group is less than that of the respective zinc group.