Answer:
The correct answers are:
"Only about 3 percent of Earth's water is fresh water."
"About 75% percent of the fresh water on Earth is frozen in ice sheets."
"The largest source of usable fresh water is groundwater."
Explanation:
3 percent of Earth's water is most certainly fresh water. Confirmed with a few fact checks.
The largest source of usable fresh water on Earth is groundwater. It's more difficult to access but it's there and much more usable than water say frozen in ice on the sea.
The most correct option left would be 75% of Earth's freshwater being in ice sheets even though it's about 70%.
Your answer would be 15 kg*m/sec
After reading and searching i found that the answer is isotope 3-45 amu is 32.88%abundant so it would be 30%