Question

Total number of sigma (\( \sigma \)) and pi (\( \pi \)) bonds respectively present in hex-1-en-4-yne are:

• A. 13 and 3
• B. 11 and 3
• C. 13 and 13
• D. 14 and 3

Hint:

When counting bonds in organic compounds, remember that each single bond is a \( \sigma \)-bond, each double bond consists of one \( \sigma \)-bond and one \( \pi \)-bond, and each triple bond consists of one \( \sigma \)-bond and two \( \pi \)-bonds.

Answer 1

The Correct Option is A

The structure of hex-1-en-4-yne consists of:
- A C=C double bond (with one \( \sigma \)-bond and one \( \pi \)-bond).
- A C≡C triple bond (with one \( \sigma \)-bond and two \( \pi \)-bonds).
- Six single bonds between carbon atoms and hydrogen atoms (each \( \sigma \)-bonds).
Count of \( \sigma \)-bonds:
- 1 \( \sigma \)-bond in the C=C double bond.
- 1 \( \sigma \)-bond in the C≡C triple bond.
- 11 \( \sigma \)-bonds between carbon and hydrogen atoms.
Thus, the total number of \( \sigma \)-bonds is 13.
Count of \( \pi \)-bonds:
- 1 \( \pi \)-bond in the C=C double bond.
- 2 \( \pi \)-bonds in the C≡C triple bond.
Thus, the total number of \( \pi \)-bonds is 3.
Therefore, the correct answer is

(1) 13 and 3.

Answer 2

Step 1: Write the structure of hex-1-en-4-yne.
Hex-1-en-4-yne has six carbon atoms with a double bond at position 1 and a triple bond at position 4.
The structural formula is:
CH₂ = CH – CH₂ – C ≡ C – CH₃

Step 2: Identify all types of bonds.
- Each single bond (C–C or C–H) is a sigma (σ) bond.
- Each double bond (C=C) contains one sigma (σ) and one pi (π) bond.
- Each triple bond (C≡C) contains one sigma (σ) and two pi (π) bonds.

Step 3: Count the sigma (σ) bonds.
1. Between carbons:
- C₁=C₂ → 1 σ
- C₂–C₃ → 1 σ
- C₃–C₄ → 1 σ
- C₄≡C₅ → 1 σ
- C₅–C₆ → 1 σ
⇒ Total C–C σ bonds = 5

2. Between C–H:
- C₁ (CH₂) → 2 H
- C₂ (CH) → 1 H
- C₃ (CH₂) → 2 H
- C₆ (CH₃) → 3 H
⇒ Total C–H σ bonds = 8

Total σ bonds = 5 (C–C) + 8 (C–H) = 13 σ bonds.

Step 4: Count the pi (π) bonds.
- One π bond from the C=C (double bond)
- Two π bonds from the C≡C (triple bond)
⇒ Total π bonds = 3

Step 5: Conclusion.
Hex-1-en-4-yne has 13 sigma (σ) bonds and 3 pi (π) bonds.

Final Answer:
\[ \boxed{13 \, \sigma \text{ bonds and } 3 \, \pi \text{ bonds}} \]