Hydrogenation reveals degree of unsaturation in hydrocarbon X Steps:

• Calculate moles of H2 gas: at room conditions, molar volume ≈ 24,000 cm³/mol, so moles H2 = 20 / 24,000 = 8.33 × 10^{-4} mol.
• Determine H2 per mole of X: 8.33 × 10^{-4} mol H2 / 0.10 mol X = 8.33 × 10^{-3} mol H2 per mol X.
• Interpret: each mol H2 corresponds to one double bond (or equivalent) hydrogenated to alkane.
• Conclude: X has ≈0.008 double bonds per molecule on average, indicating high saturation or large molecule with minimal unsaturation.

Not enough information: Choices A–D not provided, preventing identification of X or confirmation of C.

Final answer: Not enough information.