Water is called compound why?​

Which of the following statements is true about planck’s law

If the particles in a sample of matter have an orderly arrangement and move only in place, the sample is a

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