Nitrogen gained 4 electrons.
Because Nitrogen's redox number went from +6 to +2, it must have gained 4 electrons (-4) in order to achieve this number. Thus, Nitrogen is reduced.
Answer:

Explanation:
The relation between frequency and wavelength is shown below as:

c is the speed of light having value 
Given, Wavelength =
nm
Also, 1 m =
nm
So,
Wavelength =
m
Thus, Frequency is:



K is unchanged. The equilibrium constant wouldn't change. it is based on le chateliers principle.
Answer:
The mole fraction of codeine is 5.4%
Explanation:
Mole fraction = Mole of solute / Total moles (Mole solute + Mole solvent)
Solute (Codeine)
Molar mass 299.36 g/m
Mass / Molar mass = Mole → 46.85 g /299.36 g/m = 0.156 moles
Solvent (Ethanol)
Molar mass 46.07 g/m
125.5 g / 46.07 g/m = 2.724 moles
Mole fraction (Codeine) 0.156 / (0.156 + 2.724) → 0.054