Question

A monoprotic acid in a $0.1$M solution ionises to $0.001\%$. Its ionization constant is:

• A. $1\times {10}^{-11}$
• B. $1\times {10}^{-3}$
• C. $1\times {10}^{-6}$
• D. $1\times {10}^{-8}$

Answer 1

The correct option is A $1\times {10}^{-11}$

Here the concentration $C=0.1M$ and $\%\alpha =0.001$

Thus ionization constant $K_a$ of the acid can be given as,

$K_a=C{\alpha }^2=0.1\times (\frac{0.001}{100}{)}^2=1\times {10}^{-11}$