Atomic number.
The atomic number is what defines the element.
You would want to make sure that you have controlled the variables properly, and if you determine that you did then you would repeat the experiment to be sure of the results.
Answer:
The mass of objects remains constant throughout the universe. This is because an object is made of he same amount of matter (atoms), no matter where you take it in the universe. If you take an object from the Earth to the moon, only the weight will change.
Explanation:
Answer:
if it gains or loses neutrons
Answer:
Extensive or inextinsive and either physical or chemical
