Question: Which of the highlighted bonds absorbs at higher $\mathbf{\nu }$in an IR spectrum?

The IR spectra are obtained by irradiating the sample with light from the IR region (5000 to 500 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$) of the electromagnetic spectrum. IR is the only one that allows for the direct identification of the functional group.

The IR region of the spectrum extends from 4000 to 625 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$.The IR region is split into three parts.

(C=O) carbonyl stretching frequency is approximately 1650${\mathrm{cm}}^{-1}$

(C=C) carbon-carbon double bond stretching frequency is approximately 1500-1600${\mathrm{cm}}^{-1}$

(C-H) stretching frequency is approximately 1340-1470${\mathrm{cm}}^{-1}$

a

This molecule has a higher frequency because the carbonyl group is present.

b

This molecule has a higher frequency because the (C=N) group is present in it.

c

A higher frequency is observed for this molecule. It has a (C=C) group.