4. Dark Energy.
This is the mysterious force causing the expansion of space. No one has ever seen this force.
Answer:
This represents radiation in ultra-violet region .
Explanation:
Energy of the orbit where n = 3 is given as follows

= -1.511 eV
Energy of the orbit where n = 1 is given as follows

= 13.6 eV
Difference of [tex]E_3 and [tex]E_1 = - 1.511+ 13.6
= 12.089 eV.
The wavelength of light having this energy in nm is given by the expression as follows
Wavelength in nm = 1244 / energy in eV
= 1244 / 12.089
= 102.90 nm
This represents radiation in ultra-violet region .
Assume that the shape of Virginia beach is rectangular.
Note that
1 km = 10³ m
1 cm = 10⁻² m
The area is
A = (15 km)*(50 km)
= (15 x 10³ m)*(50 x 10³ m)
= 7.5 x 10⁸ m²
Because 2 cm of rain fell, the volume is
V = (7.5 x 10⁸ m)*(2 x 10⁻² m) = 1.5 x 10⁶ m³
Answer: 1.5 x 10⁶ m³