The periodic table is useful tool for chemist since we can see what is the atomic and mass number for each atom.
Atomic number is equal to how many protons and electrons in it
Mass number is equal to protons + Neutrons.
        
             
        
        
        
Answer:
Anions electronic configuration is given by adding electrons.
 
        
             
        
        
        
The number of bacteria is given by:
N(t) = N(o) x 2ⁿ
Where N(t) is the number after n hours have passed and N(o) is the original number which is 15.
The number grown in the 12th hour is the difference in the number after the 11th and the 12th hour. Thus:
15 x 2¹² - 15 x 2¹¹
= 30,720 bacteria
        
             
        
        
        
It is a Physical property because like water it changes into a ice cube but it can be melted into water or be turned back into an ice cube.