Answer:
1 g
Explanation:
The half-life of Am-242 (16 h) is the time it takes for half of it to disappear.
We can make a table of the mass left after each half-life.

The mass remaining after 48 h is 1 g.
Salt water contains minerals other than salt.
The temperature of ocean water is affected by the depth of the water.
The temperature of ocean water is affected by the ocean’s location.
Objects float more easily in oceans than in lakes or rivers.
These are all of the true answers
D. or C. I think it is more D. than anything else