I have no clue, please help and explain! =)

Question

Find the pH of a 0.150 M solution of a weak monoprotic acid having Ka=1.2×10−5.

Find the percent dissociation of this solution.

Find the pH of a 0.150 M solution of a weak monoprotic acid having Ka=1.4×10−3.

Find the percent dissociation of this solution.

Find the pH of a 0.150 solution of a weak monoprotic acid having Ka= 0.11.

Find the percent dissociation of this solution.

Answer 1

I need help =(

Answer 2

and thank you!