Question

Indicate whether the following vibrations are active or inactive in the IR spectrum.

Short answer

Following table shows the result

Step-by-step solution

Step 1. Given information

Given molecule and motion as below:

Use following concept

A molecule has the net dipole moment it is active in the infrared spectrum. The vibrations are classified into the two categories.

1. The stretching vibration: interatomic distance is changes continuously
2. The bending vibration : angle between the two bonds changes

The bending vibrations are further classified into four categories.
1. The wagging vibration.
2. The twisting vibration.
3. The rocking vibration.
4. The scissoring vibration.

Step 2. Detail table

The table below shows the molecule and motion with their active / Inactive in IR Spectrum