<u>Answer:</u> The amount of sample left after 20 years is 288.522 g and after 50 years is 144.26 g
<u>Explanation:</u>
We are given a function that calculates the amount of sample remaining after 't' years, which is:

Putting values in above equation:


Hence, the amount of sample left after 20 years is 288.522 g
Putting values in above equation:


Hence, the amount of sample left after 50 years is 144.26 g
Answer:
1.25 hours or 75 minutes or 1 hour and 15 minutes
Explanation:
The atomic mass would not change since the mass of an electron is negligible compared to the mass of protons and neutrons
<span>A full valence electron shell.</span>
Matter is everything and everything is made of matter, everything physical at least