I NEED HELP ASAP IN ON TIMER Why was Becquerel’s experiment a first step in discovering radioactivity?

A. It showed that a substance could phosphoresce when it was not exposed to light.

B. It showed that the substance that was used by Becquerel could phosphoresce.

C. It showed that a substance could constantly emit radiation even if it was not exposed to light.

D. It showed that a substance emitted radiation when it was exposed to light.

In a sample of oxygen gas at room temperature, the average kinetic energy of all the balls stays constant. which postulate of kinetic molecular theory best explains how this is possible? a. attractive forces between gas particles are negligible because the particles of an ideal gas are moving so quickly. b. collisions between gas particles are elastic; there is no net gain or loss of kinetic energy. c. gases consist of a large number of small particles, with a lot of space between the particles. d. gas particles are in constant, random motion, and higher kinetic energy means faster movement.

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 standard unit of measure for acceleration?