Cellular phones use D. microwaves.
<span>an unbalanced force is Forces that are not equal</span>
Answer:
I would say a pond
Explanation:
A pond is more still than an ocean, therefore you could see your reflection better
Via half-life equation we have:

Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes. By plugging those values in we get:

There is 6.25 grams left of Ra-229 after 12 minutes.