When 25 $\times$ 10^-2 mol of Nicotinic Acid (A Monoprotic Acid)is Dissolved in Acid)is

Multiple Choice

When 2.5 $\times$ 10^-2 mol of nicotinic acid (a monoprotic acid) is dissolved in 350 mL of water,the pH is 3.05.Calculate the K_a of nicotinic acid.

A) 1.3 $\times$ 10^-2
B) 1.1 $\times$ 10^-5
C) 7.1 $\times$ 10^-2
D) 3.3 $\times$ 10^-5
E) none of these