JEE Main 2022 · 28 Jun · Shift 2 · Chemistry Q64

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ChemistrySingle correct+4 / -1Question 64 of 90

A student needs to prepare a buffer solution of propanoic acid and its sodium salt with pH 4. The ratio of $\dfrac{\left[\mathrm{CH_3CH_2COO^-}\right]}{\left[\mathrm{CH_3CH_2COOH}\right]}$ required to make buffer is ______.

Given : $K_a\left(\mathrm{CH_3CH_2COOH}\right)=1.3\times10^{-5}$

0.03

0.13

0.23

0.33

Answer and worked solution

Official answer: B

Henderson. $\dfrac{[\text{salt}]}{[\text{acid}]}=\dfrac{K_a}{[\mathrm H^+]}=\dfrac{1.3\times10^{-5}}{10^{-4}}=0.13$ .

(B)

Topics:Buffer solutions

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JEE Main 2022 · 28 Jun · Shift 2, Chemistry question 64