The final temperature of the mixture : 21.1° C
<h3>Further explanation </h3>
The law of conservation of energy can be applied to heat changes, i.e. the heat received / absorbed is the same as the heat released
Q in(gained) = Q out(lost)
Heat can be calculated using the formula:
Q = mc∆T
Q = heat, J
m = mass, g
c = specific heat, joules / g ° C
∆T = temperature difference, ° C / K
Q ethanol=Q water
mass ethanol=

mass water =

then the heat transfer :

The accepted concentration of chlorine is 1.00 ppm that is 1 gram of chlorine per million of water.
The volume of water is
.
Since, 1 gal= 3785.41 mL
Thus, 
Density of water is 1 g/mL thus, mass of water will be
.
Since, 1 grams of chlorine →
grams of water.
1 g of water →
g of chlorine and,
of water →86.6 g of chlorine
Since, the solution is 9% chlorine by mass, the volume of solution will be:

Thus, volume of chlorine solution is 9.62\times 10^{2} mL.
B: Painting over a metal surface in order to prevent rust is known as
rust proofing and it works by preventing oxygen and water from reaching
the metal surface thus preventing a redox reaction which would result in
rusting.