What is the mass of nh3 in a 80.0-cm3 sample that has a density of 0.92 g/cm3 and consists of 20% (by mass) nh3?

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line