$7$ kg of Water at T$=20\backslash$deg C are mixed with $1$ kg of Ethanol at T Boiling. Calculate: a$)$T after mixing in $[\backslash$deg C$]$ ; b$)$Heat needed to vaporize all system$[\backslash$Delta H in Kcal$/$kg$]$ ; c$)$ concentration of last drop of liquid $[$c$\%].$ Use plot Enthalpy$/$concentration : FIGURE $2-$