6th Grade Science question on Mass, Volume, and Density!! I've tried and tried and I can't figure it out!

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

When a septic tank backs up a goes in to clean it out

What is the molar mass of a gas that has density of 2.054 g/l