Answer:
C-14 from fossil had reached itshalf life
Explanation:
For radiactive isotopes (such as Carbon-14), per definition; the semi life or semi disintegration period; is defined as the time for which a certain mass isotope mass disintegrates to half of the atoms that make it up
For Carbon-14, this semi life period is 5730 years , and for the above example, as it is mentioned that we originally had 254 grams of C-14 but we currently have 127 grams (this is, exaclt half of the original mass of 254 grams), this leads us that 5730 years have passed since the original mass and the final mass (that is, one semi life period of C-14)
Well Primary Succession means you are the first organisms of that area after it is destroyed completely or if it's new. Secondary Succession is when an area is not destroyed completely but the organisms that remain colonize the area again. I believe it's C.
The most suitable option for the first question is definitely <span>stratus clouds which usually stratch over the sky creating overcasts.
The next one should be </span><span>nimbus, as they dark and usually help to predict the storm.
And the last one </span>cumulonimbus that point on thunderstorms and so on.
