Chemical compounds secreted by mammals and insects to communicate sexual readiness are called

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

The number of neutrons is equal to the atomic number minus the atomic mass. a. true b. false

What causes most sediment to wash or fall into a river