question 15\nwhat is the stretching frequency (in cm⁻¹) of the following carbonyl?\n1685\n1745\n1715\nnone…

question 15\nwhat is the stretching frequency (in cm⁻¹) of the following carbonyl?\n1685\n1745\n1715\nnone of the above
Answer
Explanation:
Step1: Identify the carbonyl type
The given carbonyl is an $\alpha,\beta -$ unsaturated cyclic ketone.
Step2: Recall frequency range
For $\alpha,\beta -$ unsaturated cyclic ketones, the carbon - oxygen stretching frequency is around 1680 - 1690 $cm^{-1}$ due to resonance and conjugation effects.
Answer:
A. 1685