$F=2-+N$

Question $2(20$ points$)$

Determine the degrees of freedom for the following systems:

$($a$)$ Pure water at the triple point.

$($b$)$ A liquid$/$vapor mixture of ethanol, methanol, and water at $100$kPa and $60C.$

$($c$)$ A liquid$/$vapor mixture of benzene and water at $100$kPa.

$($d$)$ A gaseous mixture of nitrogen and oxygen at $25C.$