We use the given masses of the reactants to calculate the moles of Mn and Cl. Empirical formula represents the simplest mole ratio of atoms present in a compound.
Moles of Mn = 
Moles of Cl =
= 0.710 mol Cl
Simplest mole ratio: 
So the empirical formula is 
Explanation:
(a)
The relation between frequency and wavelength is shown below as:
c is the speed of light having value
Given, Wavelength = 505 nm
Also, 1 m =
nm
So,
Wavelength =
m
Thus, Frequency is:
(b)
Also,
Where,
h is Plank's constant having value
c is the speed of light having value
So,


(c)
Electromagnetic spectrum is range of the frequencies and their respective wavelengths of the various type of the electromagnetic radiation.
In order of the increasing frequency and the photon energy and the decreasing wavelength the spectrum are:
Red , Orange, Yellow, Green, Blue, Indigo, Violet
Increasing wavelength is the opposite trend. Thus, The longest visible wavelength is red and the shortest is violet.
Metals have the ability to conduct electricity.
Metals are lustrous, malleable, ductile and are good conductor of heat and electricity.
They conduct electricity because the electrons in metal are delocalized electrons and are free moving electrons so when they gain energy (heat) they vibrate more quickly and can move around, this means that they can pass on the energy more quickly.