Which of the following match is/are correct regarding B, Al, C and Si elements?

Options

A. The highest first ionisation ethalpy : C
B. The largest atomic size: Al
C. The most negative electron gain enthalpy : C
D. The most metallic character: Al

Answer

To determine which of the statements regarding the elements B (Boron), Al (Aluminum), C (Carbon), and Si (Silicon) are correct, we will analyze each statement step by step.

### Step 1: Analyze the First Statement
**Statement:** Highest first ionization enthalpy of Carbon.

**Explanation:**
- Carbon (C) is a non-metal and has a high ionization energy due to its small atomic size and high electronegativity.
- Non-metals generally have higher ionization enthalpies compared to metals.
- Therefore, this statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement:** Largest atomic size of Aluminum.

**Explanation:**
- Atomic size generally increases down a group in the periodic table due to the addition of electron shells.
- Aluminum (Al) is in group 13 and has a larger atomic size than Boron (B), which is in group 13 but above Aluminum.
- However, when comparing it to other elements in the same period or groups, Aluminum does not have the largest atomic size among B, C, and Si.
- Therefore, this statement is **incorrect**.

### Step 3: Analyze the Third Statement
**Statement:** Most negative electron gain enthalpy of Carbon.

**Explanation:**
- Electron gain enthalpy is the energy change when an electron is added to a neutral atom in the gas phase.
- Carbon, being a non-metal, has a relatively high electron gain enthalpy, but it is not the most negative among the elements listed.
- Typically, elements like Halogens have more negative electron gain enthalpies than Carbon.
- Therefore, this statement is **incorrect**.

### Step 4: Analyze the Fourth Statement
**Statement:** Most metallic character of Aluminum.

**Explanation:**
- Metallic character increases down a group and decreases across a period.
- Aluminum (Al) is a metal and has a more metallic character than Boron (B), which is a metalloid.
- Among the elements listed, Aluminum does exhibit a significant metallic character, but it is not the most metallic character compared to elements further down the group.
- Therefore, this statement is **correct**.

### Conclusion
Based on the analysis:
- **Correct Statements:** 1st (Highest first ionization enthalpy of Carbon) and 4th (Most metallic character of Aluminum).
- **Incorrect Statements:** 2nd (Largest atomic size of Aluminum) and 3rd (Most negative electron gain enthalpy of Carbon).

### Final Answer
The correct matches regarding B, Al, C, and Si elements are:
- Statement 1: Correct
- Statement 2: Incorrect
- Statement 3: Incorrect
- Statement 4: Correct