pH of an amine solution

You will finish a small calculator for the pH of a solution of a weak base. It uses the pKb, the concentration and the quadratic equation for the hydroxide ion concentration.

The idea. For a base of concentration $c$ with the constant $K_b$, the hydroxide ion concentration is the positive root of $x^2 + K_b x - K_b c = 0$. Then pOH is $-\log_{10} x$ and pH is 14 minus pOH.

Your tasks.

1. Complete kb(pkb) so that it returns $K_b$ from the pKb.
2. Complete hydroxide(pkb, c) so that it returns $[\text{OH}^-]$ from the quadratic formula.
3. Complete ph(pkb, c) so that it returns the pH.
4. Set strongest to the name of the base with the smallest pKb.