$1.$ If the distribution coefficient $($K$)$ for a solute between water and an organic solvent is $4,$ how much solute will be in the organic layer compared to the water layer?

$2.$ A batch extraction process uses $100$ mL of solvent to extract a solute from $200$ mL of feed. What is the solvent to feed ratio?

$3.$ In a ternary phase diagram, if two components A and B are present in equal amounts $(50\%),$ what is the percentage of component C$?$

$4.$ A counter$-$current extraction process with $3$ stages achieves a solute recovery of $90\%$ in the first stage, $80\%$ in the second stage, and $70\%$ in the third stage. What is the overall recovery percentage?