It's because of Avagadro's number.
- It is known as Avagadro's constant too.
- It states that at constant temperature one mole of any substance contain same number of atoms i.e n no of atoms
where

Trace fossils provide us with indirect evidence of life in the past, such as the footprints, tracks, burrows, borings, and feces left behind by animals, rather than the preserved remains of the body of the actual animal itself. so i would say B.
If it is a really humid warm day, have you ever noticed that's when all electrical storms occur
Answer :
121.5 <span>
μCi
Explanation : We have Ce-141 half life given as 32.5 days so if the activity is 3.8 </span><span>μci after 162.5 days of time elapsed we have to find the initial activity.
We can use this formula;
</span>

3.8 /

=

((0.693 X 162.5 ) / 32.5) = 121.5
<span>
On solving we get, The initial activity as 121.5 </span>μci
Answer: 4 hours
Explanation:
It takes the kayak 1 minute to travel 35 meters.
Divide the total (8400m) by the amount of meters per minute (35m)

Now convert into hours. (Remember that 1h has 60min)