The answer to the question is C
Answer is: Yes it is balanced. It has the same number of Ca and O on both the reactant side and the product side.
According to principle of mass conservation, number of atoms must be equal on both side of chemical reaction.
There is one calcium atom atom and one oxygen atom on both side of reaction, so chemical reaction is balanced.
Answer:
FAS concentration = 1.61*10^-4M
Explanation:
Beer Lambert's law relates the absorbance (A) of a substance to its concentration (c) as:

where ε = molar absorption coefficient
l = path length
A plot of 'A' vs 'c' gives a straight line with slope = εl
In addition absorbance (A) is related to % Transmittance (%T) as:
A = 2-log%T----(2)
For the FAS solution, the corresponding calibration fit is given as:
y = 3678(x) + 0.056
This implies that the slope = εl = 3678
It is given that %T = 25.6%

Based on equation(1):
