1. Tardigrade
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  3. Chemistry
  4. A weak monobasic acid is 1 % ionized at 1 M. Thus, percentage ionisation of the acid at 4 M is

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Q. A weak monobasic acid is $1 \%$ ionized at $1 M$. Thus, percentage ionisation of the acid at $4 M$ is

Equilibrium

Solution:

$HA + H _{2} O \rightleftharpoons H _{3} O ^{+}+ A ^{-}$

$K_{a}=\frac{C x^{2}}{(1-x)}$, when $C=1 M, x=0.01\, \dots(i)$

$K_{a}=\frac{C' y^{2}}{(1-y)}$, when $C=4 M , y=$? $\dots(ii)$

From Eqs. (i) and (ii)

$\frac{1 \times x^{2}}{(1-x)}=\frac{4 y^{2}}{(1-y)}$

$\frac{(0.01)^{2}}{(1-0.01)}=\frac{4 y^{2}}{(1-y)}$

$\frac{4 y^{2}}{(1-y)}=1.0 \times 10^{-4}$

$\frac{y^{2}}{1-y}=0.25 \times 10^{-4}$

$=y^{2}=0.25 \times 10^{-4}$

$y=5 \times 10^{-3}$

Thus, percentage $=5 \times 10^{-3} \times 100=0.5 \%$