100 mL solution (I) of buffer containin 0.1 (M) HA and 0.2 (M)`A^-`, is mixed with another solution (II) of 100 mL containing 0.2 (M) HA and 0.3 (M) `A^-` . After mixing, what is the pH of resulting solution ?
[Given: `pK_a` of HA=5]