<span>Charles' law says "at a constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature".
V </span>α T
Where V is the volume and T is the temperature in Kelvin of the gas. We can use this for two situations as,
V₁/T₁ = V₂/T₂
V₁ = 2.00 L
T₁ = 40.0 ⁰C = 313 K
V₂ = ?
T₂ = 30.0 ⁰C = 303 K
By applying the formula,
2.00 L / 313 K = V₂ / 303 K
V₂ = (2.00 L / 313 K) x 303 K
V₂ = 1.94 L
Hence, the volume of the balloon at 30.0 ⁰C is 1.94 L
We will see that the volume of the unit cell is 144,070,699.06 pm^3
<h3>
How to get the volume of a body-centered cubic unit cell?</h3>
In a body-centered cubic unit cell, the side length of the cube is given as:

Where R is the radius of the atom.
And the volume of a cube is the side length cubed, then we can see that the volume of our cube will be:

Solving that we get:

This is the approximated volume of the unit cell.
If you want to learn more about unit cell structures, you can read:
brainly.com/question/13110055
The correct answer is option C, that is, it is reduced.
In reduction and oxidation reactions, reduction refers to the loss of an oxygen atom from a molecule or the gaining of one or more electrons. A reduction reaction is observed from the perspective of the molecule being reduced, as when one molecule gets reduced, another one gets oxidized. The complete reaction is called a redox reaction.
In the given case, iron gains electrons mean that it is reduced.
Nonmetal your welcome
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I have provided the steps and solution within the attachment. The pH of the solution would be 12.30, this indicates that the solution is basic, as a higher value of pH indicates presence of more hydroxide ions and less of hydrogen ions in the solution.