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A solution of 0.1 M NaZ has PH = 8.90. T...

A solution of `0.1 M NaZ` has `PH = 8.90`. The `K_a` of `HZ` is.

A

`6.3 xx 10^-11`

B

`6.3 xx 10^-10`

C

`1.6 xx 10^-5`

D

`1.6 xx 10^-6`

Text Solution

Verified by Experts

The correct Answer is:
C
`NaZ` is salt of `W_A//S_B`
`:. pH = (1)/(2) (pK_w + pK_a + log C)`
`8.9 xx 2 = 14 + pK_a + log 0.1`
`17.8 = 14 + pK_a - 1`
`pK_a = 4.8`,
`K_a = "anti"log (-4.8) = Antilog (-4 - 0.8 -1)`
=`Anilog (overline (5).2) = 1.585 xx 10^-5 ~~ 1.6 xx 10^-5`.
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