A student is comparing physical versus chemical changes using sugar cubes. Which part of the student's experiment illustrates a chemical change?

A
Melting a sugar cube using a hotplate

B
Burning a sugar cube in a flame

C
Dissolving a sugar cube in water

D
Crushing a sugar cube with a mortar and pestle

Johnny rode his bike 4 blicks down the street to his friend's house once he got to his friend house and realized he could not cone out to play he turned aroubd and went back home.what is displacement for the total bike ride? how did you determine this? what could we use as a reference point to determine he was in motion during his bike ride? why can you use it as a reference point