Number of carbon atoms in alkane having molecular mass 86 is

Explanation

To find the number of carbon atoms in an alkane with a molecular mass of 86, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the General Formula for Alkanes**:
- The general formula for alkanes is \( C_nH_{2n+2} \), where \( n \) is the number of carbon atoms.

2. **Calculate the Molecular Mass**:
- The molecular mass of an alkane can be calculated by adding the mass contributions from carbon and hydrogen:
\[ \text{Molecular Mass} = (n \times \text{Atomic Mass of Carbon}) + ((2n + 2) \times \text{Atomic Mass of Hydrogen}) \]
- The atomic mass of carbon (C) is 12 g/mol and that of hydrogen (H) is 1 g/mol.

3. **Set Up the Equation**:
- Plugging in the values, we have:
\[ 86 = (n \times 12) + ((2n + 2) \times 1) \]
- This simplifies to:
\[ 86 = 12n + 2n + 2 \]
- Combine like terms:
\[ 86 = 14n + 2 \]

4. **Solve for \( n \)**:
- Subtract 2 from both sides:
\[ 84 = 14n \]
- Divide both sides by 14:
\[ n = \frac{84}{14} = 6 \]

5. **Conclusion**:
- The number of carbon atoms in the alkane is \( n = 6 \).

### Final Answer:
The number of carbon atoms in the alkane having a molecular mass of 86 is **6**.