$3.$Which equation is used to determine the minimum number of theoretical plates required for a given separation in a distillation column?

a$)$ Underwood equation

b$)$ Gilliland equation

c$)$ McCabeThiele method

d$)$ Fenske equation

The Underwood equation is used for:

a$)$ Determining the optimum reflux ratio

b$)$ Estimating the total number of theoretical plates in a distillation column

c$)$ Calculating the relative volatility of components

d$)$ Analyzing vapor$-$liquid equilibrium data

Flash distillation is often employed in:

a$)$ Industrial wastewater treatment

b$)$ Fractional distillation of crude oil

c$)$ Purification of essential oils

d$)$ Production of pure gases from mixtures

Steam distillation is a technique commonly used for the extraction of:

a$)$ Aromatics from non$-$volatile substances

b$)$ Essential oils from plant materials

c$)$ Crude oil from natural reservoirs

d$)$ Heavy metals from aqueous solutions