The number of sigma and pi bonds in benzene are:

• a. 6 sigma and 3 pi bonds
• b. 12 sigma and 3 pi bonds
• c. 9 sigma and 3 pi bonds
• d. 6 sigma and 6 pi bonds

To determine the number of sigma and pi bonds in benzene, we first need to understand its structure. Benzene is a well-known aromatic hydrocarbon with the chemical formula C6H6. It consists of six carbon atoms arranged in a ring, with alternating double bonds, and each carbon atom is bonded to one hydrogen atom.

Understanding Bond Types

In organic chemistry, bonds between atoms can be classified into two main types: sigma (σ) bonds and pi (π) bonds. Sigma bonds are formed by the head-on overlap of atomic orbitals, while pi bonds result from the side-to-side overlap of p orbitals. In a double bond, one bond is a sigma bond and the other is a pi bond.

Analyzing Benzene's Structure

Benzene has a planar, cyclic structure with the following characteristics:

• Each carbon atom forms four bonds.
• In benzene, each carbon atom is bonded to one hydrogen atom and shares a double bond with adjacent carbon atoms.

Counting the Sigma Bonds

In benzene, each of the six carbon atoms forms:

• One sigma bond with a hydrogen atom.
• One sigma bond with each of its two neighboring carbon atoms.

This gives us:

• 6 sigma bonds between carbon and hydrogen (1 for each of the 6 hydrogen atoms).
• 6 sigma bonds between the carbon atoms (each carbon is bonded to two other carbons).

So, the total number of sigma bonds in benzene is:

6 (C-H) + 6 (C-C) = 12 sigma bonds

Counting the Pi Bonds

Now, let's look at the pi bonds. In benzene, there are three alternating double bonds. Each double bond consists of one sigma bond and one pi bond. Therefore, the total number of pi bonds in benzene is:

3 pi bonds

Final Count of Bonds

Summarizing our findings:

• Total sigma bonds: 12
• Total pi bonds: 3

Thus, the correct answer to the question about the number of sigma and pi bonds in benzene is:

b. 12 sigma and 3 pi bonds

This understanding of benzene's bonding structure is crucial in organic chemistry, especially when discussing its stability and reactivity compared to other hydrocarbons.