What does the half-life of a radioactive substance indicate? A. It indicates how dangerous the substance is to humans.
B. It indicates how much energy is released over time.
C. It indicates how long it takes for the material to decay.
D. It indicates how long it takes until all radioactivity is gone

Does anyone know a lot about how to: - calculate mass of magnesium metal - calculate the actual yield of magnesium oxide - calculate the theoretical yield of mgo - calculate the percent yield of mgo - determine the percent yield of mgo - determine the average percent yield of mgo i had to do an online lab and its asking these questions but i have no idea where to start or how to be able to find these things. i can post the chart of the data from the lab or if you can tell me exactly how i can find each.

An exothermic reaction is conducted in an insulated calorimeter filled with water. the calorimeter is then sealed so that there is no heat exchanged between the contents of the container and the surrounding air. which of the following statements is true about the reaction?

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer