Which of the following statements is false?

Options

A. sigma bond is shorter than that of pi bond
B. Bond energies of `sigma` and `pi` bonds are of the order of 264 and 347 kJ/mol respectively
C. Free rotation of atoms about sigma bond is allowed but not in case of pi bond
D. pi bond results from lateral overlap of atomic orbitals

Answer

To solve the question of which statement is false, we will evaluate each of the four statements provided.

### Step 1: Analyze Statement 1
**Statement:** Sigma bond is shorter than that of pi bond.

**Analysis:** This statement is true. Sigma bonds are formed by end-to-end overlapping of orbitals, which results in a stronger bond due to greater overlap. As a result, sigma bonds are generally shorter than pi bonds, which are formed by lateral overlapping.

### Step 2: Analyze Statement 2
**Statement:** Bond energies of sigma and pi bonds are of the order 264 and 374 kJ per mole respectively.

**Analysis:** This statement is false. The bond energy of a sigma bond is typically higher than that of a pi bond due to the stronger overlap. The correct bond energies are approximately 347 kJ per mole for sigma bonds and 264 kJ per mole for pi bonds. Therefore, the values given in this statement are incorrect.

### Step 3: Analyze Statement 3
**Statement:** Free rotation of atoms about sigma bond is allowed but not in case of pi bond.

**Analysis:** This statement is true. Sigma bonds allow for free rotation because the electron density is concentrated along the internuclear axis. In contrast, pi bonds do not allow for free rotation due to the presence of a nodal plane and the lateral overlap of orbitals.

### Step 4: Analyze Statement 4
**Statement:** Pi bond results from lateral overlap of atomic orbitals.

**Analysis:** This statement is true. Pi bonds are indeed formed by the lateral overlap of p orbitals. In contrast, sigma bonds are formed by end-to-end overlap.

### Conclusion
After analyzing all statements, the false statement is **Statement 2**: "Bond energies of sigma and pi bonds are of the order 264 and 374 kJ per mole respectively."

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