Degree of unsaturated in `C_xH_8` is two. The value of x is …............

Answer

To find the value of \( x \) in the molecular formula \( C_xH_8 \) given that the degree of unsaturation is 2, we can follow these steps:

### Step 1: Understand the Degree of Unsaturation Formula
The degree of unsaturation (DU) can be calculated using the formula:
\[ DU = \frac{C - H + X + N}{2} + 1 \]
where:
- \( C \) = number of carbon atoms
- \( H \) = number of hydrogen atoms
- \( X \) = number of halogens (which is 0 in this case)
- \( N \) = number of nitrogen atoms (which is also 0 in this case)

### Step 2: Substitute the Known Values
In our case, we have:
- \( H = 8 \)
- \( X = 0 \)
- \( N = 0 \)

So the formula simplifies to:
\[ DU = \frac{x - 8 + 0 + 0}{2} + 1 \]
We know that \( DU = 2 \).

### Step 3: Set Up the Equation
We can set up the equation based on the degree of unsaturation:
\[ 2 = \frac{x - 8}{2} + 1 \]

### Step 4: Solve for \( x \)
Now, we will solve for \( x \):
1. Subtract 1 from both sides:
\[ 2 - 1 = \frac{x - 8}{2} \]
\[ 1 = \frac{x - 8}{2} \]

2. Multiply both sides by 2:
\[ 2 = x - 8 \]

3. Add 8 to both sides:
\[ x = 2 + 8 \]
\[ x = 10 \]

### Conclusion
The value of \( x \) is 10. Therefore, the molecular formula is \( C_{10}H_8 \).