You did not provide the statements but a possible answer might be that the current atomic theory is sound and that technology that could challenge it does not exist at this time. There is no way to change it because no research can be done about it.
The mass of the liquid is 280 g.
Mass = 200 mL × (1.4 g/1 mL) = 280 g
Answer:
Only the number of neutrons change.
Your drawing looks so good :p
