Number of possible alkynes with formula `C_5H_8` is

Options

A. 3
B. 5
C. 2
D. 4

Explanation

To determine the number of possible alkynes with the formula C₅H₈, we will follow these steps:

### Step 1: Understand the General Formula for Alkynes
Alkynes are hydrocarbons that contain at least one triple bond. The general formula for alkynes is CₙH₂ₙ₋₂, where n is the number of carbon atoms.

### Step 2: Calculate the Value of n
For the given formula C₅H₈, we can see that:
- The number of carbon atoms (n) is 5.
- We can check if it fits the general formula for alkynes:
- For n = 5, the formula should be C₅H₂(5) - 2 = C₅H₈.

This confirms that C₅H₈ is indeed an alkyne.

### Step 3: Identify Possible Structures
Now we will identify the possible structural isomers of alkynes with the formula C₅H₈:
1. **1-Pentyne**: The triple bond is between the first and second carbon atoms.
- Structure: CH≡C-CH₂-CH₂-CH₃

2. **2-Pentyne**: The triple bond is between the second and third carbon atoms.
- Structure: CH₃-C≡C-CH₂-CH₃

3. **3-Methyl-1-butyne**: The triple bond is between the first and second carbon atoms, but with a methyl group on the third carbon.
- Structure: CH₃-C≡C-CH₃-CH₃ (or CH₃-CH₂-C≡C-CH₃)

### Step 4: Count the Isomers
From the above analysis, we have identified three distinct alkynes:
1. 1-Pentyne
2. 2-Pentyne
3. 3-Methyl-1-butyne

Thus, the total number of possible alkynes with the formula C₅H₈ is **3**.

### Final Answer
The number of possible alkynes with the formula C₅H₈ is **3**.

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