$pOH = 7 - 0.5 p K_{a} + 0.5 p K_{b}$ is true for an aqueous solution that has which pair of cations and anions amongst the following?

C_{6} H_{5} N H_{3}^{+}, C H_{3} C O O^{-}

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N H_{4}^{+}, F^{-}

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N a^{+}, C H_{3} C O O^{-}

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N H_{4}^{+}, C l^{-}

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Solution

The correct option is B $N H_{4}^{+}, F^{-}$
$pOH = 7 - 0.5 p K_{a} + 0.5 p K_{b}$ , this equation for calculating $p O H$ is valid for salt of week acids and week bases
Now $(C_{6} H_{5} N H_{2}, C H_{3} C O O H$ ) and $(N H_{3}, H F)$
both are WA and WB pairs so this equation will be valid for them
In rest of the options, either the acid or the base is strong.

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Similar questions

pOH = 7 - 0.5 p K_{a} + 0.5 p K_{b}

pOH = 7 - 0.5 p K_{a} + 0.5 p K_{b}

p O H = 7 - 0.5 {p K}_{a} + 0.5 {p K}_{b}

p o H = 7 - 0.5 p K_{A} + 0.5 p K_{b}

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