What characteristic of radioactive decay makes it useful for determining the absolute age of samples?
2 answers:
Answer:
Option A, occurs at a constant rate
Explanation:
It becomes easy to determine the age of any radioactive substance when the rate of decay is constant and its starting and presents mass is known.
For example - if we know that the mass of a radioactive substance is 100 Kg few years back , but its present mass is 10 Kg. Then if we know the value of rate of decay, we can easily determine the age of substance based on the logarithmic equation as given below
Where is the mass of radioactive substance at time t
is the mass of radioactive substance at time
t is the time in years and
k is the decay constant.
Hence, option A is correct.
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Answer:
The correct answer is C and Engelmann conducted this experiment to prove relationship between algae and the rate of photosynthesis.
Explanation: First we must talk about 3 facts:
1) Prism scatters the white light into different wavelengths.
2) Photosynthesis, 6 carbon dioxide and 6 water molecules are consumed and 6 oxygen and 1 sugar molecule is synthesized using light energy.
6CO2 + 6H2O → C6H12O6 + 6O2
3) Aerobic bacteria breaks down sugar while using oxygen and produces water and carbon dioxide in simplified terms.
So with this experimental setup a researcher can understand the rate of the photosynthesis by increased accumulation of aerobic bacteria near algae in certain wavelengths since they uses oxygen and tend to move close to the oxygen source (<u>see figure</u>). In this experiment there are no ways to measure heat (B), there is no known relation between wavelength of light and aerobic respiration since it can happen even in the dark (A) and finally there are no ways to measure carbon dioxide (D).
