Why are surfaces often good catalysts for bimolecular reactions? explain.

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

What is the atomic number of an atom that has 6 protons

How many moles are in 7.2 x 10^23 carbon molecules?