"An aqueous solution contains 0.34 M hydrocyanic acid. 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.)"

0.34mol NaCN

0.082mol Ba(OH)₂

Explanation:

Options:

0.34mol NaCN

0.33mol NaClO₄

0.34mol HClO₄

0.16mol HClO₄

0.082mol Ba(OH)₂

A buffer is defined as the aqueous mixture of a weak acid with its conjugate base or vice versa.

Hydrocyanic acid, HCN is a weak acid. Its equilibrium in water is:

HCN + H₂O → CN⁻ + H₃O⁺

Where the CN⁻ ion is the conjugate base.

Thus, to convert the HCN solution in a buffer you must add CN⁻ ions to the solution.

In solution, 0.34mol NaCN converts 0.34 mol CN⁻, thus, you can convert this solution in a buffer with this addition.

The addition of HClO₄ or NaClO₄ don't produce a buffer because you would not have CN⁻ ions in solution.

Now, HCN reacts with Ba(OH)₂ thus:

2HCN + Ba(OH)₂ → 2H₂O + Ba²⁺ + 2CN⁻

Thus, the addition of 0.082mol Ba(OH)₂ could convert this solution in a buffer because CN⁻ is produced in its reaction with HCN

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.