If you had 4.9 moles of Ba(BrO3)2, how many atoms of barium, bromide, and oxygen would you have?

D) Ratio of acetic acid to sodium acetate in the buffer falls.

Explanation:

A buffer is a solution that maintains the pH almost unaltered. It's formed by weak acid and its conjugate base, or a weak base and its conjugate acid. Normally we make a buffer mixing the acid or base with a salt that contains its conjugate.

In the buffer will have an equilibrium, so by adding an acid or a base in the solution, the compounds such regulate the concentration of ions H₃O⁺ and OH⁻. The buffer has a limit: it can make the pH unaltered in pKa +/- 1. pKa is the -log Ka, where Ka is the constant of the equilibrium of the acid.

So, adding a large quantity of sodium hydroxide, which is a base, during a certain time the buffer will work out, but the rate of equilibrium will fall and the pH will increase because there'll be no more ions to neutralize the OH⁻ of NaOH.

If the initial pH was 6.76, the pH will increase more; if the water was unbuffered, than, the pH will increase more (there'll be no ions to neutralize OH⁻); and sodium acetate may not form a precipitate, because it's a salt formed by a strong base, so it's very soluble.