Question

Hydrocyanic acid ($K_a=4.8\times {10}^{-10}$) is dissociated to an extent of .......... in $1.0M$ solution

• A. $0.0022$%
• B. $0.022$%
• C. $0.0048$%
• D. None of these

Answer 1

The correct option is A $0.0022$%

$\Rightarrow$ $K_a={\alpha }^{2}C$ (for weak electrolyte)

$4.8\times {10}^{-10}={\alpha }^2\times 1.0$

$\alpha =\sqrt{4.8\times {10}^{-10}}$

$=2.19\times {10}^{-5}$

$0.000022$

$\therefore$ Percent dissociation $=0.000022\times 100$

$=0.0022$%