First ionization energy is highest for :

Options

A. Lead
B. Carbon
C. Silicon
D. Tin

Explanation

To determine which element has the highest first ionization energy among lead (Pb), carbon (C), silicon (Si), and tin (Sn), we can follow these steps:

### Step 1: Understand Ionization Energy
First, we need to understand what ionization energy is. Ionization energy is the energy required to remove an electron from an isolated gaseous atom.

**Hint:** Remember that ionization energy is affected by the atomic size and the effective nuclear charge.

### Step 2: Identify the Group of Elements
Next, we identify the elements in the question:
- Carbon (C)
- Silicon (Si)
- Tin (Sn)
- Lead (Pb)

These elements belong to the same group in the periodic table, known as Group 14 (or IV A).

**Hint:** Group elements tend to show trends in their properties as you move down the group.

### Step 3: Analyze the Trend in Ionization Energy
In general, as you move down a group in the periodic table, the ionization energy decreases. This is because:
- The atomic size increases due to the addition of electron shells.
- The outermost electrons are further away from the nucleus and experience less attraction due to increased shielding from inner electrons.

**Hint:** Consider how the atomic size and shielding effect influence the ionization energy.

### Step 4: Compare the Elements
Now, let's compare the elements:
- Carbon (C) is at the top of the group.
- Silicon (Si) is below carbon.
- Tin (Sn) is below silicon.
- Lead (Pb) is at the bottom of the group.

According to the trend, carbon will have the highest ionization energy because it is the smallest atom in this group and has the highest effective nuclear charge acting on its outermost electron.

**Hint:** Recall that smaller atoms generally have higher ionization energies.

### Step 5: Conclusion
Based on the analysis, the element with the highest first ionization energy among the options given is Carbon (C).

**Final Answer:** Carbon (C)