Question

In which bending type of vibration bond angle is constant?

• A. Scissoring
• B. Twisting
• C. Rocking
• D. All of the above

Answer 1

The Correct Option is C

Step 1: Understanding molecular vibrations. - Molecular vibrations are categorized into stretching and bending. - Bending vibrations include scissoring, rocking, wagging, and twisting. 

Step 2: Explanation of bond angle changes in bending vibrations.
 - Scissoring: Involves movement of atoms towards or away from each other, changing the bond angle. 
- Twisting: A torsional motion where one part of the molecule moves opposite to another, changing the bond angle. 
- Rocking: Movement occurs in the plane but does not change bond angles. 

Step 3: Explanation of incorrect options. 
- (A) Scissoring: Incorrect, as it changes bond angles. 
- (B) Twisting: Incorrect, as it involves torsional deformation. 
- (D) All of the above: Incorrect, as only rocking keeps the bond angle constant. 

Step 4: Selecting the correct option. Since rocking vibration keeps the bond angle unchanged, the correct answer is (C) Rocking.