Question

$pH$ of a centimolar solution of a mono basic acid is $6$. The dissociation constant is approximately equal to:

• A. ${10}^{-12}$
• B. ${10}^{-8}$
• C. ${10}^{-10}$
• D. ${10}^{-6}$

Answer 1

Answer: (C)

${10}^{-10}$

Given, the concentration of $\left[H^{+}\right]={10}^{-pH}={10}^{-6}$ and concentration of solution, $\left[C\right]=0.01M$
Now,
$\left[H^{+}\right]=\sqrt{K_a\times C}$
$=>{10}^{-6}=\sqrt{K_a\times 0.01}$
$=>K_a$ (dissociation constant) $={10}^{-10}$