Cox chart, which is useful in the design of distillation column particularly for petroleum hydrocarbons, is a plot of (where, P = vapor pressure, T = temperature)

ANS:A - log P vs . T

The Cox chart, which is particularly useful in the design of distillation columns for petroleum hydrocarbons, is a plot of log P (vapor pressure) vs. T (temperature). This chart is valuable for designing distillation columns because it allows engineers and designers to visually analyze the relationship between vapor pressure and temperature for various hydrocarbon components. Understanding this relationship is crucial for determining the appropriate operating conditions, such as reflux ratio, reboiler temperature, and column pressure, to achieve efficient separation of the hydrocarbon mixture in the distillation process.