Two cyclists start at the same point, but travel along two straight streets in different directions. if they continue, how many times will their paths cross again?

Since they are travelling on two different straight directions, therefore their paths will NEVER cross again. This because straight lines will keep on going forever on the same direction therefore there is 0 possibility for two straight lines to paths cross again.

zero or never

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.