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The PK(a) of a weak acid is 5.85. The co...

The `PK_(a)` of a weak acid is `5.85.` The concentrations of the acid and its conjugate base are equal at a pH of -

A

`6.85`

B

`5.85`

C

`4.85`

D

`7.85`

Text Solution

Verified by Experts

The correct Answer is:
B
`pH = pK_(a) +log. (["Conjugate base "])/(["Acid"])`
` :. ["Conjugate base "] = ["Acid"] `
`pH = pK_(a) = 5.85`
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