Can i have an example of both a physical and chemical change taking place at the same time. it can't be burning a candle, food chewing and digestion, and burning wood.

The answer for #3 is c but i don't know why

In which of these cases are the two wave points considered to be in phase with each other?

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