Estimate the viscosity of the fluids in the following cases. $($a$).-$ Estimate the viscosity of cyclohexane at $210$ C and toluene at $280$ C$.$ The gases are at low pressures. Use the Chapman$-$Enskog equation and compare with nomogram values. $($b$).-$ Estimate the viscosity of liquid n$-$heptane at $18$ C$.($c$).-$ Viscosity data is available for mixtures of hydrogen and Freon $12$ at $25$ C and $1$ atm. Compare the calculated values with the experimental data at $0\mathrm{.}25$ and $0\mathrm{.}75$ mole fraction of hydrogen. $($d$).-$ Estimate the viscosity of a $25-75$ mol $\%$ ethane$-$propane mixture a

$\backslash$table$[[\backslash$table$[[$Fracci$$n mol$],[$de hidr$$geno$]],\backslash$table$[[$Viscosidad de la$],[$mezcla $(x{10}^5)Pa.S$t $285$ C and P$=2\mathrm{.}026$x$107$ Pa$.$