Answer:
A
Explanation:
To label an element correctly using a combination of the symbol, mass number and atomic number furnishes some important information about the element. 
We can obtain these information from the element provided that correct labeling of the element is presented. Firstly, after writing the symbol of the element, the atomic number is placed as a subscript on the left while the mass number of the atomic mass is placed as a superscript on the same left.
Looking at the question asked, we have the element symbol in the correct position as Ca, with 42 also in the correct position which is the mass number. The third number which is 20 is thus the atomic number of the element. 
 
        
             
        
        
        
Answer:
The Answer would be B (Materials can be seen in picometers which are trillionths of a meter or the size atoms.
Explanation:
 
        
             
        
        
        
Answer:
Tug of War
An object sinking in water
Kicking a ball
 
        
                    
             
        
        
        
Answer:
I'm pretty sure its stimulus