Please help me with my 8th grade chemistry, I'm really confused
The Law of Conservation of Mass states that mass can neither be created nor destroyed. In which of the following situations does this law apply?
a. in neither chemical nor physical changes
b. only in chemical changes
c. in both chemical and physical changes
d. only in physical changes

Liquid from a brewery fermentation contains 10% ethanol and 90% water. part of the fermentation product (50,000 kg/h) is pumped to a distillation column on the factory site. under current operating conditions, a distillate of 45% ethanol and 55% water is produced from the top of the column at a rate of one-tenth that of the feed. what is the composition of the waste "bottoms" from the still?