Subject :NSO Class : Class 6
What is common among the following phenomena?
1. Planetary motion
2. Blinking of traffic lights
3. Motion of rotating fan blades
4. Swinging of a pendulum
AThey are all chemical changes.
BThey are all periodic changes.
CThey are all undesirable changes.
DThey are all physical changes.
Ans 1:
Class : Class 9
I think that it is option D