Explanation:
elctronic configuration of manganese
Mn=1s²2s²2p⁶3s²3p⁶4s²3d⁵
ground state
Mn=Ar3d⁵4s²
note that Ar is argon
Two types of stoichiometry are; molar mass and coefficients from balanced equation.
Answer:
The concentration is 
Explanation:
From the question we are told that
The absorbance is 
The length is 
Generally absorbance is mathematically represented as

where
is the molar absorptivity of FeSCN2 with a value 
and
is the equilibrium concentration of FeSCN2
So

substituting values

