Help me with the for the exam

Which of these is a density dependent factor? a. epidemic b. earthquake c. drought d. hurricane

A2-kg bowling ball is 1 meter off the ground on a post when it falls. just before it reaches the ground, its traveling 4.4 m/s. assuming that there is no air resistant, which statement is true a. the initial potential energy is less then the final kinetic energy b. the mechanical energy is not conserved c. the mechanical energy is conserved d. the initial potential energy is greater than the final kinetic energy

How many grams of oxygen gas will react completely with a block of calcium metal that is 3.0 cm by 3.5 cm by 4.2 cm, if the density of calcium is 1.55 g/ml? show all steps of your calculation as well as the final answer.