Nitrogen-12 was able to be used in an experiment, but it took 243 seconds to get the nitrogen from the reactor to the laboratory. If 12.0mg of nitrogen-12 was removed from the reactor, how many mg were placed in the reaction vessel 243 seconds later if the half-life of nitrogen-12 is 81 seconds?

Alice did an experiment to find the relationship between the angle at which a ray of light strikes a mirror and the angle at which the mirror reflects the light. she placed a ray box in front of a mirror. she changed the angle at which the light from the ray box struck the mirror and noted the corresponding angle at which the mirror reflected the light. which of the following is the dependent variable in this experiment? the mirror used to reflect the light the ray box used as the source of light angle at which the light from the ray box strikes the mirror angle at which the mirror reflects the light from the ray box