Both mammal and fish embryos contain gill slits. Similarly, whales, some snakes, and land animal embryos all exhibit hind limbs. How do the similarities in these developing organisms show relationships not evident in the fully formed anatomy?

CN^-1 is the conjugate base of the weak acid HCN ( Ka 3 X 10^-9 )so CN^-1 is a strong base and will hydrolyze, by the reaction:
CN^-1 + H2O --> HCN + OH^-1

The amount is based on the hydrolysis constant which is
Kw / KaHCN = 1 X 10^-14 / 3 X 10^-9
= 3.333 X 10 ^-6

0.2 M CN^-1 will ionize to a small extent ( A ) to produce A amounts of HCN and A amounts of OH^-1

soo Kh = 3.333 X 10^-6 = [A][A] / 0.2 -A
but A <<< 0.2 ( much lesser than)  so it will be omitted in the denominator

A^2 = 0.2 x 3.333 X 10^-6
 A^2= 6.67 X 10^-7
A= 8.17 X 10^-4

 pOH = -log ( 8.17 X 10^-4 ) = 3.09
then ph is
pH = 14 - pOH
so
pH = 14 - 3.09
pH = 10.91