Answer:
The mass number of an atom is its total number of protons and neutrons. Atoms of different elements usually have different mass numbers , but they can be the same. For example, the mass number of argon atoms and calcium atoms can both be 40.
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This type of classification used to be used when classifying the protostome organisms.
In this type of organism, the oral cavity develops from the blastophore, the initial cavity in the gastrula, an early stage of the development of the embryo.
        
             
        
        
        
Answer:
A cell cycle is a series of events that takes place in a cell as it grows and divides
Explanation:
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