Which of the following molecules will have polar bonds but zero dipole moment ?

Options

A. `O_(2)`
B. `CHCl_(3)`
C. `CF_(4)`
D. none of these

Answer

To determine which molecule has polar bonds but a zero dipole moment, we need to analyze the molecular geometry and the electronegativity of the atoms involved in the bonds. Here’s a step-by-step solution:

### Step 1: Understand Polar Bonds
- A polar bond occurs when there is a difference in electronegativity between two atoms, resulting in a shift of electron density towards the more electronegative atom. This creates a partial positive charge on one atom and a partial negative charge on the other.

**Hint:** Remember that polar bonds arise from differences in electronegativity.

### Step 2: Identify the Molecules
- The molecules we need to analyze are:
1. Oxygen gas (O2)
2. Chloroform (CHCl3)
3. Carbon tetrafluoride (CF4)

**Hint:** List the molecules clearly to analyze them one by one.

### Step 3: Analyze Oxygen Gas (O2)
- In O2, both atoms are oxygen, which means they have the same electronegativity. Therefore, the bond is non-polar, and there are no polar bonds or dipole moments.

**Hint:** Check if the atoms in a molecule are identical; if they are, the bond is non-polar.

### Step 4: Analyze Chloroform (CHCl3)
- In chloroform, the bonds between carbon and chlorine (C-Cl) are polar because chlorine is more electronegative than carbon. However, the molecule has a tetrahedral shape, which means the dipoles do not cancel out completely due to the asymmetrical arrangement of the bonds. Thus, chloroform has a net dipole moment.

**Hint:** Consider the molecular geometry to see if the dipoles cancel out.

### Step 5: Analyze Carbon Tetrafluoride (CF4)
- In CF4, the bonds between carbon and fluorine (C-F) are polar because fluorine is highly electronegative. However, CF4 has a symmetrical tetrahedral shape. The dipoles from each C-F bond are equal in magnitude and symmetrically arranged, leading to cancellation of the dipoles. Therefore, CF4 has polar bonds but a net dipole moment of zero.

**Hint:** Symmetrical molecules with polar bonds can have a zero dipole moment.

### Conclusion
- The molecule that has polar bonds but a zero dipole moment is **Carbon Tetrafluoride (CF4)**.

**Final Answer:** CF4 has polar bonds but a zero dipole moment.