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: 
Step-by-step explanation: In some cases you must apply the exponent rule, simplify, or multiply them together to get your answer.
Answer: 16, 18
Step-by-step explanation:
16 + 18 = 34
Answer:
The percent of error in her measurement is 1.3%
Step-by-step explanation:
we know that
The circumference of a circle is equal to

where
D is the diameter
we have

assume

substitute
----> This value represent the 100% (theoretical value)
Find the difference between the theoretical value and the measured value
Find the percentage by proportion
