Q15 / 160 · AP EAMCET 2021 (24 Aug Shift 1) · Chemistry

Which among the following pair constitute a buffer?

  • A
    $\mathrm{LiOH}$ and $\mathrm{LiCl}$
  • B
    $\mathrm{HNO}_3$ and $\mathrm{NH}_4 \mathrm{NO}_3$
  • Correct answer
    C
    $\mathrm{HNO}_2$ and $\mathrm{NaNO}_2$
  • D
    $\mathrm{HBr}$ and $\mathrm{KBr}$

Solution

Buffer solution consists of mixture of weak acids and their salts or weak base and their salts. $\mathrm{LiOH}$ is a strong base whereas $\mathrm{HNO}_3$ and $\mathrm{HBr}$ are strong acids. $\mathrm{HNO}_2$ is a weak acid and $\mathrm{NaNO}_2$ is a salt formed by combination of weak acid $\left(\mathrm{HNO}_2\right)$ and strong base $(\mathrm{NaOH})$. Buffer $=\mathrm{HNO}_2+\mathrm{NaNO}_2$.

Hence, the correct answer is option: 'C'.

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