Final answer:
The anxiolytic drug Valium (diazepam) with the molecular formula C16H13ClN2O has 7 degrees of unsaturation.
Step-by-step explanation:
The degree of unsaturation, also known as the index of hydrogen deficiency (IHD), can be calculated by the formula: IHD = (2C + 2 + N - X - H)/2. In the molecular formula C16H13ClN2O, there are 16 carbon atoms (C), 13 hydrogen atoms (H), 1 chlorine atom (Cl), 1 nitrogen atom (N), and 2 oxygen atoms (O). Plugging these values into the formula gives us: (2(16) + 2 + 1 - 0 - 13)/2 = 7. Therefore, the number of degrees of unsaturation in the molecule is 7.