D) An atom with 4 protons, 3 neutrons, and 3 electrons
We can say that the water is the solvent, and the powder is the solute. This is also a solution altogether.
Explanation:- A solute is the thing being dissolved into the solvent. While the solvent is what when the solute is being dissolved in. Together, they make a solution.
"NH4+ <----> NH3 + H+
The constant of this equilibrium is: K = Kw / Kb = 1 x 10^-14 / 1.8 x 10^-5 =5.56 x 10^-10
5.56 x 10^-10 = x^2 / 0.20-x
x = [H+] =1.1 x 10^-5 M
pH = 5.0"