Answer:
Step-by-step explanation:
As an example, iodine-131 is a radioisotope with a half-life of 8 days. It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131.
50 grams to 25 grams is one half-life. 25 grams to 12.5 grams is another half-life. So, for 50 grams to decay to 12.5 grams, two half-lives, which would take 36 days total, would need to pass. This means each half-life for element X is 18 days.
Answer:
Sorry i don't know......!!!!!!!
Step-by-step explanation:
Answer:
B
Step-by-step explanation
the answer comes to 
and 15 is the only answer below 20
Any number multiplied by one keeps its identity
You're going to set up a proportion. % over 100 = is over of. You're looking for the percent so that's your x. X over 100=7 over 25. Cross multiply to get 25x=700. Divide both sides by 25 and your answer is 28%
