An aqueous solution contains 0.30 M potassium fluoride.
One liter of this solution could be converted into a buffer by the addition of:.
(Assume that the volume remains constant as each substance is added.)
A. 0.15 mol NaOH
B. 0.30 mol HNO3
C. 0.29 mol HF
D. 0.29 mol KBr
E. 0.15 mol HNO3

A. 0.15 M NaOH, and

E. 0.15 M HNO3

Explanation:

A buffer solution contains a conjugate acid-base pair with both the acid and the base in reasonable concentrations.

NaOH and HNO3 is an acid base pair with relatively equal concentrations. So, they would most likely make a buffer solution.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.