Answer:
2.2 grams
Step-by-step explanation:
We can use the compound decay formula shown below to solve this:

Where
F is the final amount (what we want to find)
P is the present amount (490 grams)
r is the rate of decay, in decimal (28.6% = 28.6/100 = 0.286)
t is the time in minutes (16)
Substituting, we get:

So, after 16 minutes, 2.2355 grams will be remaining.
<em>Rounded to nearest tenth of a gram (1 decimal place) = </em><em>2.2 grams remaining</em>