A steel melt contains $0\mathrm{.}074$ wt$.\%$ C$,0\mathrm{.}92$ wt$.\%$ Cr$,$ and $1\mathrm{.}04$ wt$.\%$ Si at $1610C.$

a$)$ Calculate the activity of carbon in the melt.

b$)$ Calculate the activity of chromium in the melt at$.$

c$)$ Calculate the activity of silicon in the melt at$.$

d$)$ Calculate the corresponding activity of oxygen if the melt is in equilibrium with $0\mathrm{.}98$atm of $CO.$

$[C{]}_{(11wT\%inFe)}+[O{]}_{(Iw+\%inFe)}=C{O}_{(g)},G{?}_T=-22384\mathrm{.}4-39\mathrm{.}66T(J)$

$(R=8\mathrm{.}314\frac{J}{m}ol.K)($The atomic weight: $C=12\mathrm{.}0,O=16\mathrm{.}0,Si=28\mathrm{.}0,Cr=52\mathrm{.}0,Fe=55\mathrm{.}9g$

Table. Interaction coefficients $(e_i^{j_{}}{10}^2)$ for dilute solutions of elements dissolved in the iron melt at $1610C.$