Question

17 mg of a hydrocarbon (M.F. C₁₀H₁₆) takes up 8.40 mL of the H₂ gas measured at \(0\degree C\) and 760 mm of Hg. Ozonolysis of the same hydrocarbon yields

The number of double bond/s present in the hydrocarbon is_______.

Hint:

For determining double bonds:
• Use the degree of unsaturation formula to find the total number of double bonds and rings.
• Analyze ozonolysis fragments to confirm the number and position of double bonds.

Answer 1

Correct Answer: 3

1. Molecular Formula Analysis:
The given molecular formula is \(\text{C}_{10}\text{H}_{16}\). The degree of unsaturation is:
\[\text{Degree of unsaturation} = \frac{2C + 2 - H}{2} = \frac{2(10) + 2 - 16}{2} = 3.\]
This indicates 3 double bonds or rings.
2. Hydrogenation Data:
8.40 mL of \(\text{H}_2\) gas is absorbed. At STP, 1 mol of gas occupies 22.4 L. Moles of \(\text{H}_2\) absorbed:
\[n = \frac{8.40}{22400} = 3.75 \times 10^{-4}~\text{mol}.\]
3. Ozonolysis Data:
Ozonolysis fragments indicate three distinct double bonds in the hydrocarbon.
4. Conclusion
The hydrocarbon contains 3 double bonds.
Final Answer: \(3\).