Answer: 2) Electron X absorbs energy when it changes to a higher energy level.
Explanation:
The electrons in an atom exist in various energy levels. When an electron moves from a lower energy level to a higher energy level, energy is absorbed by the atom. When an electron moves from a higher to a lower energy level, energy is released (often as light).
Proton gives nucleus positive charge P+
Radioactive material undergoes 1st order decay kinetics.
For 1st order decay, half life = 0.693/k
where k = rate constant
k = 0.693/half life = 0.693/8.02 = 0.0864 day-1
Now, for 1st order reaction,
k =

Given: t = 6.01d, initial conc. = 5mg
∴0.0864 =

∴ final conc. = 2.975 mg
C = vf
c stands for the speed of waves (which is a constant that is 3 x 10^8)
v stands for the wavelength (which is given)
f stands for frequency (what we are solving for)
3 x 10^8 = (1.08 x 10^-6)f
Divide both sides by the given wavelength
f = 2.78 * 10^14 seconds