Answer: The answer of the first problem is isotopes. The answer of the second problem is proton. The answer of the third problem is neutron.
Step-by-step explanation:
Isotopes are the species having the same atomic number but having different mass number. The example of the isotopes is the three forms of hydrogen. The three forms of hydrogen are protium, dueterium and tritium.
In isotopes, there are equal number of protons but there is different number of neutrons.
To find the number of neutron, calculate the difference of the mass number and the atomic number.
Therefore, the answer of the first problem is isotopes. The answer of the second problem is proton. The answer of the third problem is neutron.