A 25 mL sample of 0.100 M HNO3 completely reacts with NaOH according to this equation:

HNO3 (aq) + NaOH (aq) ⟶ NaNO3 (aq) + H2O (l)

How many moles of HNO3 are in the sample?

⇒ 0.0025 mol HNO3

What volume of 0.0500 M NaOH solution is required to completely react with the HNO3?

If someone could teach me how to do this, it would be awesome

It is a good thing that you already have answered the first question. Now, moving on to the second question, there exist an equation for the neutralization of acid by a base that is shown below,

M₁V₁ = M₂V₂

Now, all the variables in the equation are given except for our unknown which is the V₂. Substituting the known values from the given above,

(0.1 M) (25 mL) = (0.05 M) (V₂)

The value of V₂ from the equation above is 50 mL. Therefore, 50 mL of 0.05 M NaOH solution will be needed to completely react with HNO3.