What system is responsible for transport and delivering

What’s the scientific notation for the number 6,840,000,000

Draw the skeletal structures of two different molecules that are each made of 5 carbon atoms and 12 hydrogen atoms.

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here