The pH of 0.01 M solution of a weak acid with K_a=4x10^-6 (neglect water ionisation and use [H+]=sqrtK_ac) is. Use log 2=0.301 and log 3=0.477 where needed. Take 298 K.

JEE Main levelSingle correct optionDifficulty 2 of 3ie070

The pH of $0.01 M$ solution of a weak acid with $K_{a} = 4 \times 1 0^{- 6}$ (neglect water ionisation and use $[H X^{+}] = K_{a} c$ ) is. Use $lo g 2 = 0.301$ and $lo g 3 = 0.477$ where needed. Take 298 K.

[H X^{+}] = 4 \times 1 0^{- 6} \times 1 0^{- 2} = 2 \times 1 0^{- 4} M

pH = 4 - lo g 2 = 4 - 0.301 = 3.70