ANS:B -

In distillation, the operating line for the rectifying section can be represented by the equation: 𝑦=𝑚⋅𝑥+𝑐y=m⋅x+c Where:

• 𝑦y is the mole fraction of the more volatile component in the liquid leaving the tray,
• 𝑥x is the mole fraction of the more volatile component in the vapor entering the tray,
• 𝑚m is the slope of the operating line,
• 𝑐c is the intercept of the operating line on the y-axis.

In terms of distillation variables, 𝑥𝐷xD​ represents the mole fraction of the more volatile component in the overhead product, and 𝑅𝐷RD​ represents the reflux ratio. The slope (𝑚m) of the operating line is given by: 𝑚=𝑅𝐷𝑅𝐷+1m=RD​+1RD​​ The intercept (𝑐c) of the operating line is given by the mole fraction of the more volatile component in the overhead product: 𝑐=𝑥𝐷c=xD​ So, the slope and intercept of the operating line for the rectifying section are respectively:

• Slope (𝑚m) =𝑅𝐷𝑅𝐷+1=RD​+1RD​​
• Intercept (𝑐c) =𝑥𝐷=xD​