If valve "D" is opened during the normal operation of the distiller shown in the illustration, which of the events listed will occur? Illustration MO-0111

Correct Answer: Option B — The amount of vapor being formed in the evaporator will decrease.

Opening valve D typically bypasses the heating medium or alters the vacuum/feed balance. In standard distiller illustrations, this action reduces the heat input to the evaporator section, directly lowering the rate of evaporation and resulting in a decrease in the amount of vapor produced for the condenser.