MCQ
Which of the following is a buffer solution ?
- AA solution of $KCl$ and $KOH$
- BA solution of $CH_3COOK$
- CA solution of $K_2SO_4$ and $NH_4OH$
- ✓A solution of $PhCOOK$ and $PhCOOH$
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[Given : $\mathrm{R}=0.083 \mathrm{~L} \mathrm{bar} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$ ]
Assume complete dissociation of $\mathrm{NaCl}$
| $I.P.$ | Reason |
| $(A)$ $N > O$ | Half filled configuration |
| $(B)$ $Zr < Hf$ | Lanthenide contraction |
| $(C)$ $Na > K$ | $Z_{eff}$ |
| $(D)$ $Al < Ga$ | Transition contraction |