Answer:
Public health is "the science and art of preventing disease", prolonging life and improving quality of life through organized efforts and informed choices of society, organizations, communities and individuals.
Explanation:
There are 18. In each molecule of Fe(NO3)2 there are 6 oxygen atoms because you have 2 nitrate (NO3) components which each contain 3 oxygen atoms. 2 x 3 = 6. Because you have 3 molecules of Fe(NO3)2, you need to multiply 6 by 3, which gives you 18 oxygen atoms.
The heat energy breaks down the bonds between the molecules of the solid so the molecules become looser. Further hearing of the liquid causes the bonds to be broken down and the molecules will move further apart.
