Answer:
1. The first three Hydrogen atoms have the same number of protons
2. The first three Hydrogen atoms are also isotopes of each other
3. The third Hydrogen atom and the first Helium atom have the same mass number
4. The second Carbon atom and the first Oxygen atom both have the same number of neutrons
Explanation:
1. The number on the top left tells us the mass number while the bottom left number tells us the atomic number. The atomic number is equal to the number of protons.
2. An isotope is when there is an equal amount of protons, but a different number of neutrons. Neutrons can be calculated by taking the mass number and subtracting the atomic number.
3. As said before, the mass number is the number on the top left of each symbol. Look for atoms with the same mass number.
4. Neutrons can be calculated by taking the mass number and subtracting the atomic number. The second Carbon atom and the first Oxygen atom both have six neutrons. 14 - 6 = 8 neutrons for the second Carbon and 16 - 8 = 8 neutrons for the first Oxygen atom.