- ✓$2$
- B$5$
- C$6$
- D$4$
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(nearest integer)
[Given : Molar mass of $\mathrm{AB}_2=200 \mathrm{~g} \mathrm{~mol}^{-1} \cdot \mathrm{K}_{\mathrm{b}}$
(molal boiling point elevation const. of water)
$=0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$, boiling point of water $=100^{\circ} \mathrm{C}$;
$\mathrm{AB}_2$ ionises as $\left.\mathrm{AB}_2 \rightarrow \mathrm{A}^{2+}+2 \mathrm{~B}^{-}\right]$

Given : $K_f (H_2O)$ = $2\ K\ kg\ mole^{-1}$, $K_{sp} (PbCl_2)$ = $4 × 10^{-6}$
(Assume molarity to be equal to molality) .....$^oC$
$\begin{array}{|c|c|c|c|}\hline {} &\text { Molisch's Test} & {\text { Barfoed Test}} & {\text { Biuret Test}} \\ \hline \text { A} & { Positive } & {\text { Negative }} & {\text { Negative }} \\ \hline \text { B } & {\text { Positive }} & {\text { Positive }} & {\text { Negative }} \\ \hline \text { C } & {\text { Negative }} & {\text { Negative }} & {\text { Positive }} \\ \hline\end{array}$
$A, B$ and $C$ are respectively