How can the height of a person who is six feet tall be expressed (approximately) in nanometres?

The size of particles being studied in 'nano-technology' is about

Assertion (A): In the visible spectrum of light, red light is more energetic than green light. Reason (R): The wavelength of red light is more than that of green light.

The branch of Physics that deals with the motion of very small particles is called :

Scientists have observed the merger of giant 'blackholes' billions of light-years away from the Earth. What is the significance of this observation?

The ratio of the diameters of moon and earth is nearly