Buffer solution is made up of weak acid or base with its conjugate salt. It resists the change in pH of the solution. When acid or base is added to the buffer solution, the pH gets stabilized but the direction of reaction is opposite. Thus, the reaction is same but the one moves backward and other moves in forward direction.
A buffer solution can be defined as:
HA +NaA
Here, NaA is in dissociated form as follows:
NaA\rightarrow Na^{+}+A^{-}
when acid is added it reacts with A^{-} to form HA and reaction moves in backward direction. When base is added it reacts with HA to form more A^{-} and reaction moves in forward direction.
If acid is added
Answer would be B. I provided work on an image attached. Message me if u have any other questions on how to do it
Answer:

Explanation:
Hello there!
In this case, since these problems about formulas, firstly require the determination of the empirical formula, assuming that the given percentages are masses, we can calculate the moles and mole ratio of oxygen to iron as shown below:

In such a way, by rounding to the first whole number we multiply by 8 and divide by 5 to obtain:

Whose molar mass is 159.69 g/mol and the mole ratio of the molecular to the empirical formula is:
479.1/159.69=3
Therefore, the molecular formulais:

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0.5 mg/mL would be expressed as 500 ug/uL
The balanced equation for the reaction is as follows
2Al + 3H₂SO₄ --> Al₂(SO₄)₃ + 3H₂
stoichiometry of Al to H₂SO₄ is 2:3
number of Al moles reacted - 15.0 mol
if 2 mol of Al react with 3 mol of H₂SO₄
then 15.0 mol of Al reacts with - 3/2 x 15.0 mol = 22.5 mol
22.5 mol of H₂SO₄ is required