Final answer:
No, an atom with 26 protons and a mass number of 52 is not expected because the mass number should equal the sum of protons and neutrons, and this is not consistent with known isotopes of the element with 26 protons (iron).
Step-by-step explanation:
No, we do not expect to find an atom with 26 protons and a mass number of 52. This is because the correct answer is d. No, because the mass number should be equal to the sum of protons and neutrons in an atom. An atom of iron, which has 26 protons, typically has more neutrons than protons, making its usual mass numbers 56 or 58 due to common isotopes. A mass number of 52 would imply that it has only 26 neutrons, which is not consistent with the known isotopes of iron.
As fundamental concepts, the atomic number defines the identity of the element and is equal to the number of protons in an atom. The mass number is the sum of the number of protons and the number of neutrons in an atom's nucleus. Electrons are not included in the mass number calculation due to their negligible mass compared to protons and neutrons. To calculate the number of neutrons, you subtract the atomic number from the mass number. An atom with 26 protons (atomic number) and a mass number of 52 would only have 26 neutrons (52 - 26). This does not match the known isotopes of iron, which have more neutrons than protons.