Answer:
The standard cell potential of the reaction is 0.78 Volts.
Explanation:

Reduction at cathode :
Reduction potential of
to Cu=
Oxidation at anode:

Reduction potential of
to Fe=
To calculate the
of the reaction, we use the equation:

Putting values in above equation, we get:

The standard cell potential of the reaction is 0.78 Volts.
The density of water at 12°C is lower than the density of water at 20°C.
Now density is related to volume as per: density = mass / volume =>
mass = volume * density.
So, the greaer the density the higher the mass of the same volume of water.
Therefore, 100.0 ml of water at 12°C has a mass greater than 100.00 ml of water at 20 °C.