1.

A weak acid HA has a `K_(a)` of `1.00 xx 10^(-5)`. If 0.100 mol of this acid is dissolved in one litre of water the percentage of acid dissociated at equilibrium is closed toA. `99.0%`B. `1.00%`C. `99.9%`D. `0.100%`

Answer» Correct Answer - B
`K_(a) = 1 xx 10^(-5)`
`{:(HA,hArr,H^(+),+,A^(-)),(.1m//l,,0,,0),(.1-x,,x,,x):}`
`10^(-5) = (x^(2))/(1-x)`
Assume `x lt lt.1`
`x^(2) = 10^(-6)` or `x = 10^(-3)`, % dissociation `= (10^(-3))/(.1) xx 100 = 1%`


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