What is a light-year?

a. the distance light travels from the sun to the earth
b. the distance light travels in one orbit of the moon
c. the distance light travels in one earth year
d. the time it takes light to travel across the universe

What is a possible quantum number set for an electron in the 3s orbital of a magnesium atom

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?

Scientists discovered fossils in several layers of the earth you see here. they found fossils of algae, snails, and clams in layer d. given that information, where do you think they found fossil evidence of simple land plants and amphibians?