The existence of an atom was first suggested by Democritus, the idea is then developed in 1803 by John Dalton.
According to Dalton's atomic theory, matter is made up of atoms which are inseparable and can not be destroyed further. For a given element, all atoms have identical mass and properties. Atoms of two different elements combine to form compounds and rearrangement of these atoms results in chemical reaction.
Answer: The equilibrium constant for the given reaction is 0.0421.
Explanation:

Concentration of
= 0.0095 M
Concentration of
= 0.020 M
Concentration of
= 0.020 M
The expression of the equilibrium constant is given as:
![K_c=\frac{[PCl_3][Cl_2]}{[PCl_5]}=\frac{0.020 M\times 0.020 M}{0.0095 M}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BPCl_3%5D%5BCl_2%5D%7D%7B%5BPCl_5%5D%7D%3D%5Cfrac%7B0.020%20M%5Ctimes%200.020%20M%7D%7B0.0095%20M%7D)
(An equilibrium constant is an unit less constant)
The equilibrium constant for the given reaction is 0.0421.
Metals usually become cations since electrons are negatively charged and when they are lost there are more protons than electrons making a positive net charge in the atom. (cations are positively charged ions while anions are negatively charged ions)
I hope this helps. Let me know if anything is unclear.
Absorbance is related to the concentration of a substance using the Beer-Lambert's Law. According to this law, absorbance is linearly related to concentration. However, this is only true up to a certain concentration depending on the substance. For this case, we assume that the said law is applicable.
A = kC
Using the first conditions, ewe solve for k.
0.26 = k (0.10)
k = 2.6
A = kC
A = 2.6 (0.20) = 0.52
Therefore, the absorbance at a concentration of 0.20 M and wavelength of 500nm is 0.52.