Answer:
idc
Explanation:
i dont understand bc i dont have this class
 
        
             
        
        
        
Answer:
An index fossil is also known as guide fossils or indicator fossil. They are fossils used to determine and identify geologic periods.
The main characteristics of an index fossil include :
1.It must be distinctive.
2.It must be widespread.
3. It must be abundant
4. It must be limited in geologic time. 
Due to trends and studies of most fossil-bearing rocks being formed in the ocean, the major index fossils are mostly marine animal or plant organisms.
 
        
                    
             
        
        
        
I need more of a sentance to anwser anything
        
             
        
        
        
Atomic number of an atom equals to the number of nucleus in the nucleus of the atom. Therefore, the answer is 74.
The proton of an element is never changed. No matter if it's an atom or ion. It's like an ID number for an element. It defines the type of element. Don't mix up atomic number with mass number though, mass number is the total sum of of the number of protons and neutrons in an atom. 
Theres one more subatomic particle in an atom, that is electrons. But since they're too light, they won't be counted in mass. Also, the number of electrons in an atom equals to the number of proton, also the atomic number. If the number of electrons is different, it's no longer an atom, but an ion.