A buffer solution is prepared by mixing $0.01 \mathrm{M}$ weak acid and $0.05 \mathrm{M}$ solution of a salt…

A buffer solution is prepared by mixing $0.01 \mathrm{M}$ weak acid and $0.05 \mathrm{M}$ solution of a salt of weak acid and strong base. What is the $\mathrm{pH}$ of buffer solution? $(\mathrm{pKa}=4.74)$
  1. $3.34$
  2. $4.80$
  3. $5.44$
  4. $6.93$

Solution

$\begin{aligned} \mathrm{pH} & =\mathrm{pK}_{\mathrm{a}}+\log _{10} \frac{[\text { salt }]}{[\text { acid }]} \\ & =4.74+\log _{10} \frac{0.05}{0.01} \\ & =4.74+0.7=5.44\end{aligned}$

Asked in: MHT CET 2023 (12 May Shift 2)

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