The table below gives information about the nucleus of each 4 atoms
atom number of protons number of neutrons
a 6 6
d 6 7
g 7 7
e 7 8
how many different elements are represented by the nuclei in the table?
a 1
b 2
c 3
d 4

The answer is B 2. As it says Atom Number of Protons and Number of Neutrons, from my understanding it means that the first number after the letter is the number of protons and the second number is the number of neutrons.

Now, If there are 6 protons in a nucleus that means there are 6 electrons on the outside, so A and D are the same element. However, you may be confused because of the different number of neutrons (6 and 7 or 7 and 8) this only means that one is and isotope of the element.

*Isotopes are atoms with the same number of protons but different number of neutrons. (Basically, same element different mass)