Question

The number of sigma \((\sigma)\) and pi \((\pi)\) bonds respectively in ethene molecule are:

• A. \(4\sigma,\ 1\pi\)
• B. \(5\sigma,\ 1\pi\)
• C. \(6\sigma,\ 1\pi\)
• D. \(5\sigma,\ 2\pi\)

Hint:

Remember: \[ \text{Single bond}=1\sigma \] \[ \text{Double bond}=1\sigma+1\pi \] \[ \text{Triple bond}=1\sigma+2\pi \]

Answer 1

The Correct Option is B

Concept: A single bond contains: \[ 1\sigma \] bond. A double bond contains: \[ 1\sigma + 1\pi \] bond. Ethene structure is: \[ H_2C=CH_2 \]

Step 1: Count C-H sigma bonds.
Each carbon atom forms two C-H single bonds. Total C-H bonds: \[ 4 \] Each single bond contributes: \[ 1\sigma \] Therefore: \[ 4\sigma \] bonds are present from C-H bonds.

Step 2: Count bonds in carbon-carbon double bond.
The: \[ C=C \] double bond contains: \[ 1\sigma +1\pi \] bond. Thus: \[ 1\sigma \] and: \[ 1\pi \] bond are contributed.

Step 3: Calculate total bonds.
Total sigma bonds: \[ 4+1=5 \] Total pi bonds: \[ 1 \] Hence: \[ \boxed{5\sigma,\ 1\pi} \]