What are carbon-12, carbon-13, and carbon-14?

different elements

different isotopes of the same element

carbon atoms with different numbers of electrons

carbon atoms with different numbers of electrons

Explanation:

Carbon-12 has 6 neutrons, carbon-13 has 7 neutrons, and carbon-14 contains 8 neutrons. Carbon-12 and 13 are stable isotopes, which means that the nucleus does not undergo radioactive decay. Carbon-14 possesses an unstable nucleus which undergoes radioactive decay

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.