general chemistry chapter 15 question

An explorer who in search of discovering relics of ancient alchemy stumbles upon an unknown weak acid of the past while searching under a cathedral in France. Luckily, for his sake, he brought his pH probe and the concentration is written in an ancient language he recognizes. It turns out the pH is 5.32 and the concentration of the solution is 0.200 M. He hands this information to you to find the ka of this acid. 

"Get 15% discount on your first 3 orders with us"
Use the following coupon
FIRST15

Order Now