Radio waves.
microwaves.
infrared waves.
light.
ultraviolet waves (rays)
x-rays.
gamma rays.
Given, half life of a certain radioactive element = 800 years.
Amount of substance remaining at time t = 12.5%
Lets consider the initial amount of the radioactive substance = 100%
Using the half life equation:
A = A₀(1/2)^t/t₁/₂
where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.
Plugging the given data into the half life equation we have,
12.5 = 100 . (1/2)^t/800
12.5/100 = (1/2)^t/800
0.125 = (0.5)^t/800
(0.5)^3 = (0.5)^t/800
3 = t/800
t = 2400 years
Thus the object is 2400 years old.
Answer:
This question is incomplete, the complete question is:
Nancy and Hiyang are training for a race. They entered some of their training notes in a chart. Which information should be added to the chart in order find out who ran a greater distance?
The answer is C). the units used to measure distance each day
Explanation:
According to the question, Nancy and Hiyang are training for a race that involves them recording the distance they ran in a chart. Distance, as a quantity, is measured using different S.I units like metres, kilometers, miles, centimeters, etc.
However, in order to accurately discover whether Nancy or Hiyang ran a greater distance as recorded in their chart, the units used to measure distance each day must be included. This is because the unit of a quantity determines how big or small it is in comparison to another. For example, 20metres is not the same as 20centimetres.
If the unit they used in measuring their distance is not included, it will be impossible to tell what is being measured, talkless of who ran a greater distance