Below is a set of UV melting curves for chymotrypsinogen at various $pH($from $J.$ Am$.$

Chem. Soc. $1964,86,20,4291-4301).$ The y$-$axis is the change in extinction coefficient

at a wavelength of $293nm.$

Fig. $1.-$The temperature dependence of the extinction coeffi$-$

cient at $293m$ : curve $1,pH1\mathrm{.}11$; curve $2,pH1\mathrm{.}71$; curve $3,$

pH $2\mathrm{.}07$; curve $4,$ pH $2\mathrm{.}56$; curve $5,$ pH $3\mathrm{.}00$; curve $6,2\mathrm{.}3M$

urea, $pH1\mathrm{.}55$; all solutions contain only $HCl($no added salt$).$

a$)$ Estimate $H(T_d),S(T_d),$ and $T_d$ for each condition listed.

b$)$ Comment on the molecular$-$level processes that may give rise to the changes in these

parameters.