Consider the reaction in aqueous solution:

$Co(N{H}_3{)}_{5}B{r}^{2+}+H{g}^{2+}$ products

a$.$ Estimate $S^{\text{\#}}$ es$.$ Explain why its sign is expected to be so$.$

b$.$ What is the effect of decreasing the solvent polarity $($decreasing ${}_r)$ on the rate constant? What is the physical reason for the predicted behavior?

c$.$ How can be the effect of ionic strength experimentally investigated?

d$.$ What is the effect of increasing the ionic strength on the rate constant? Explain your answer.