Consider the cell reaction at 300 K .

$$ A(s)+B^{2+}(a q) \rightleftharpoons A^{2+}(a q)+B(s) $$

Its $E^{\ominus}$ is 1.0 V . The $\Delta_r H^{\ominus}$ of the reaction is $-163 \mathrm{kJmol}^{-1}$.

What is $\Delta_r s^{\ominus}$ (in $\mathrm{JK}^{-1}$ ) of the reaction?

$$ \left(F=96500 \mathrm{C} \mathrm{~mol}^{-1}\right) $$

The rate constant of a first order reaction was doubled when the temperature was increased from 300 to 310 K . What is its approximate activation energy (in $\mathrm{kJ} \mathrm{mol}^{-1}$ )? ( $R=8.3 \mathrm{Jmol}^{-1} \mathrm{~K}^{-1}: \log 2=0.3$ )

Which of the following solutions is used in the styptic action which prevents bleeding of blood?

' $A$ ' is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of gold sol to which 1 mL of $10 \% \mathrm{NaCl}$ is added. What is the gold number of ' $A$ '?

Expt. No.	Wt (in mg ) of $\boldsymbol{A}$ added to gold sol	$$ \text { Coagulation } $$
1	40	Prevented
2	35	Prevented
3	25	Not prevented
4	32	Not prevented
5	33	Prevented