Question

[There is a big water container for the experiment. We can see an orange floating on the water.]
The air pockets make "a)the orange" lighter than the water, so it floats.
How , then, can you sink "b)the orange"?
...It sinks because "c)the orange" is now denser than the water.
-----------------------------------
Thank you for your help. One more questions as follows.
a), b), c) Are they used as a specific orange? Or in generic use?

Answer 1

All are referring to one particular orange in that container of water, yes.