$4-$ Given the isocline for a ferrochrome and nickel alloy taken at $T=650C$ and $P=1$atm,

a$)$ For a melt composition of $70wt\%Cr,20wt\%Ni,10wt.\%Fe($Even#$),60wt\%Cr,30wt\%Ni,10$ wt$.\%Fe($odd#$),$ find out the phases in equilibrium and their wt$.$ percentages $(2\mathrm{.}5P)$

b$)$ Find out approximately the $Ni,Cr,Fe$ concentrations of the phases you have determined in $($a$)(2\mathrm{.}5$P$)($Blue lines are tie lines connecting solid solutions in equilibrium$)$

c$)$ Apply phase rule $($or thermodynamic equilibrium conditions$)$ for the conditions given in $Q4(5P)$