Number of proton and newton of calcium

What mass of carbon dioxide is produced from the complete combustion of 4.50×10−3 g of methane?

Consider the elements bromine and chlorine; which elements has a larger ionic radius ?

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