Answer:
The energy in its ground state is 10 meV.
Explanation:
It is given that,
The energy of the electron in its first excited state is 40 meV.
Energy of the electron in any state is given by :

For ground state, n = 1
.............(1)
For first excited state, n = 2
.............(2)
Dividing equation (1) and (2), we get :


So, the energy in its ground state is 10 meV. Hence, this is the required solution.
Answer:
3 m/s
Explanation:
Average Speed = 
Plug in the numbers, it will be (6m + 3m) divided by (2s + 1s), which is 9m/3s, which equals to 3m/s.
Answer: Enceladus
Explanation:
Enceladus is a small, icy body with an undergound ocean beneath its crust. Cassini discovered that geyser-like jets spew water vapor and ice particles. It is also the sixth largest moon in Saturn and just about a tenth of the largest moon in Saturn; Titan. It is often regarded as one of the most reflective body in the solar system as a result of its icy surface.
The FREQUENCY of light remains unchanged once it leaves the source.