Answer and Explanation:
The Fremy salt is a chemical compound its chemical name is disodium nitrosodisuphonate
The molecular formula of the Fremy salt is
When phenol is treated with Fremy salt in presence of water then benzoquinone is formed
( in presence of Fremy salt and water)
The frequency : a) 7.5 x 10¹⁴ /s
<h3>Further explanation</h3>Radiation energy is absorbed by photons
The energy in one photon can be formulated as
Where
h = Planck's constant (6,626.10⁻³⁴ Js)
f = Frequency of electromagnetic waves (/s or Hz)
f = c / λ
c = speed of light
= 3.10⁸ m/s
λ = wavelength
The wavelength(λ) of purple light is 400 x 10⁻⁹ m, so the frequency :