The electronegativity values of C,H,O,N and S are 2.5, 2.1, 3.5, 3.0 and 2.5 respectively. Which of the following is the most polar?

Options

A. O-H
B. S-H
C. N-C
D. C-H

Answer

To determine which bond is the most polar among the given options based on the electronegativity values of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S), we will follow these steps:

### Step 1: Understand Electronegativity and Polarity
Polarity in a bond arises due to the difference in electronegativity between the two atoms involved in the bond. The greater the difference in electronegativity, the more polar the bond.

### Step 2: Identify the Electronegativity Values
The given electronegativity values are:
- C: 2.5
- H: 2.1
- O: 3.5
- N: 3.0
- S: 2.5

### Step 3: Calculate the Electronegativity Differences for Each Bond
We will calculate the electronegativity difference (ΔEN) for each bond option:

1. **OH bond:**
- Electronegativity of O = 3.5
- Electronegativity of H = 2.1
- ΔEN = 3.5 - 2.1 = **1.4**

2. **SH bond:**
- Electronegativity of S = 2.5
- Electronegativity of H = 2.1
- ΔEN = 2.5 - 2.1 = **0.4**

3. **NC bond:**
- Electronegativity of N = 3.0
- Electronegativity of C = 2.5
- ΔEN = 3.0 - 2.5 = **0.5**

4. **CH bond:**
- Electronegativity of C = 2.5
- Electronegativity of H = 2.1
- ΔEN = 2.5 - 2.1 = **0.4**

### Step 4: Compare the Electronegativity Differences
Now we will compare the calculated ΔEN values:
- ΔEN (OH) = 1.4
- ΔEN (SH) = 0.4
- ΔEN (NC) = 0.5
- ΔEN (CH) = 0.4

### Step 5: Determine the Most Polar Bond
The bond with the highest electronegativity difference is the most polar. From our calculations, the OH bond has the highest ΔEN of 1.4.

### Conclusion
Thus, the most polar bond among the given options is the **OH bond**.

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